17 KDE Plasma Features That You Didn't Know About

KDE Plasma is just packed with features, some of which, even long term plasma users might not know about. I have been using the Plasma desktop for many years now and I am still finding new cool features. Here is a list of 17 cool features of KDE Plasma that you probably didn't know about.
My FrontPageLinux.com Article ►► frontpagelinux...
In addition to this video, I made an article on FrontPageLinux.com that shows more specific details about these features as well as my personal settings for how I customize these features in my setup. If you'd like to see how my workflow is configured. Each tip that I customize will have a note at the bottom for how I customize it.
5 Reasons Why I Use KDE Plasma ►► • 5 Reasons Why KDE Plas...

[@simewn]

I have a shortcut that saved me when I was writing my thesis. When there are many windows open, like 50 pdf files, you press the shortcut to show all windows and it is a mess, because of the too many open windows. So, let's say I want to find the pdf that has the word "Steve" in the title. I am starting typing and it filters out the opened windows! That is brilliant!

[@michael_tunnell]

This is a great tip too! I've used this many times even sometimes not on purpose lol I think this should be included in the next video. :)

[@REDGTA]

We need a master KDE Plasma guide. Never understood why the devs packed so many features into this DE but never showcase them.

[@michael_tunnell]

That is a big task but that could be something that I'll eventually make

[@REDGTA]

@@michael_tunnell Yeah, that would be like writing a novel. I wonder do the KDE devs document this stuff when it's added?

[@ps5hasnogames55]

because so many of these features are old and have been forgotten about / aren't maintained much or at all. why else do you think kde is so buggy lol

[@lawrencedoliveiro9104]

You could try looking at the docs. (Base64 decode) aHR0cHM6Ly91c2VyYmFzZS5rZGUub3JnL1R1dG9yaWFscyNQbGFzbWE=

[@loucipher7782]

because desktop linux is basically a dumpster they mostly just make n throw in then forget about it with no maintenance its mostly trial n error either you found a gem or crap but mostly its filled with crap

[@vkohli17]

Thanks a ton for this - can't believe I didn't know about meta+click for drag and meta+right click to resize, and they're such life savers!

[@michael_tunnell]

I agree! Super useful features! 😎👍

[@venanks]

Wow! I have been using KDE since version 1.1, there are many hidden gems I didn't know. Thanks a lot.

[@felipekinoshita]

Recently a new effect was introduced "overview", right now it's basically a present windows copy but since it was done from scratch, it's way more flexible now so it'll be really easy to add for example virtual desktop previews like in parachute or macOS's mission control, if everything goes as expected it should be the default on Plasma 5.23!

[@FengLengshun]

Ooh, how do I activate that once it lands? Could you bind it to a mouse button as well? Gnome Activity Overview is the main reason why I stuck with Gnome.

[@felipekinoshita]

@@FengLengshun Meta+Ctrl+D, this could change though

[@michael_tunnell]

I like the Meta + Control + D as the shortcut. That has my vote

[@michael_tunnell]

I recorded this video right before I heard of the new overview and I'm super excited about this! It will make my video out of date a bit but totally worth it lol 😎👍

[@FengLengshun]

@@felipekinoshita I'll probably rebind it to Meta (Alt + F1) is possible, and would it be possible to bind it to a hot corner as well? Well, I could probably just xbindkeys a corner to it anyways. Still, I hope I could soon test this in Manjaro - WPS theming was one of my issue with KDE before and that's solved too, so I'd be free to switch between GNOME and KDE soon.

[@medve23]

Michael, I have been a Linux user since 2000, and used KDE most of the time, although I have ventured to other DEs every now and then. Thanks for putting this video together. I will make sure to direct all others to your channel, when they need help with KDE tricks and customizations. Well Done!

[@shariarrahman7562]

I just love KDE so much

[@raymondgradzewicz]

I knew a lot of this, but CTRL + F10 and CTRL + F8 were extremely useful! I never knew these things were in KDE.

[@michael_tunnell]

Glad you found this video helpful 😎👍

[@KdeOrg]

Thanks for the video!

[@tell1998]

A much needed video. You forgot to mention global mute, I think everyone would love to know how to do that especially when everything is now virtual

[@michael_tunnell]

I did forget to do that, good suggestion. Looks like I'm going to have to do another one of these. I had a few that I had to bump off because I already had so many so a part 2 is probably in order. 😎👍

[@tell1998]

@@michael_tunnell I'm ready for part 2 😏

[@michael_tunnell]

Lol it may have to wait longer than a day

[@zeniktorres4320]

@@michael_tunnell Yes please do part 2 for folks like me coming from gnome.

[@TheofilosIntzoglou]

Thanks for the useful tips! I have one too for the window transparency in case noone mentioned it. If you go to system settings ->Window Management->Window Behavior->Titlebar Actions you can set Mouse Wheel to change the window opacity.

[@edbeckerich3737]

I have KDE Tunnell vision now, thanks Michael!!

[@blackchristiangeek]

Thank you brother, I have been using KDE Plasma for awhile now since switching to Linux as my daily driver and have learned a lot already. Thanks again and God bless,

[@michael_tunnell]

you're welcome! I am glad you enjoyed the video! :D

[@jaquekod815]

that 3rd tip is SO USEFUL

[@guilherme5094]

A really nice and useful video, thank you Michael.

[@peterschmidt9942]

The window resize is a good one although not particular needed so much with KDE as you can generally grab the window edges easily in KDE. Not so much in many other Linux distros where it really is needed. This is one of many reasons I gravitated towards KDE - window resizing just works as it should and one real annoyance with other DE that don't get it right. I'm still relatively new to KDE so still nutting out all the cool features it has. Thanks for showing more!

[@Hero337]

Man, You just blown my mind with some of them.

[@btfrenchy]

I'm new to KDE and love borderless but it's inconvenient to get the menu back. I didn't think of setting up a shortcut, duh, so thank you!

[@michael_tunnell]

You're welcome 😎👍

[@samazer]

I had no idea about the Window Move and Resize keys. The idea of adding a shortcut for toggling window borders is also brilliant :) Thank You :)

[@michael_tunnell]

You're welcome, glad it helped 😎👍

[@atreusduvelll600]

Great video and article, Michael! Lots of things I didn't know in here. I will need to give Plasma a try again :) Thanks!

[@Wilhuf1]

Good tips. I configured my window behavior| Titlebar actions so that I can mousewheel to change window transparency.

[@AgentTex13]

Putting this in my watch later list for when I make the switch to linux in a few short weeks

[@gamerboy4566]

Thanks for the very useful video. Learnt a lot about KDE.

[@esquilo_atomico]

That onde about resizing is amazing. Thanks bro

[@michael_tunnell]

You're welcome 😃 I'm glad you found something useful in the video

[@jotarokujo6099]

Activities are a hidden gem too!

[@michael_tunnell]

Agreed! I'll probably include this in a part 2 if I make one of those. I did have to bump off a few other things so it's looking likely I will do another

[@JohanAdrian]

Thank you so much. I discovered some nice tricks here!

[@eodor180]

wow, glad I knew almost about every feature but zooming. thanks for that

[@sridhartn83]

Very informative and most I didnt know, thanks. For tiling you can press shift + left mouse to arrange the Windows in tiles and super + T to set the tiling configuration or pattern.

[@vcrbetamax]

Thank you for this video! I didn't know about most of these. I'm fresh from windows and my idea of what the super key does, is just bring up the menu. When you said super key, I thought you meant the function button at first.

[@michael_tunnell]

I'm glad you found the video helpful 😃

[@RicardoPerezLeon]

I love KDE Plasma.

[@ButImFeelingMuchBetterNow]

KRunner is one I have known about since starting with KDE (Thanks Noah). I use alt-space, go get a coffee, and by the time I get back it is up and ready for me to start searching. Ok, it isn't quite that slow, but it is slow enough to start for me that I pretty much never use it. I find it much faster to use the search bar in the Kickoff Application Launcher. 1000 Thanks! for Super + mouse drag to move windows. As already mentioned in the comments, this used to be Alt and drag. Since it changed, I never learned what the new key command is. Now this will be fantastic for me. And another 1000 thanks for Super + arrow keys. I was fairly sure KDE had this ability, but again I had never investigated how to do it. And now I can completely scrap messing with tiling window managers for good (Sorry, DT. I tried, I really did).

[@cjpartridge]

What hardware are you running? I use KRunner religiously on several systems with a bunch of plugins, and it's always very responsive.

[@FengLengshun]

KRunner was kind of hit and miss for me on my older laptop as well running Manjaro KDE. It is very good for something built in but sometimes it works well, sometimes it doesn't. Story of KDE really - you just have to try and see if it works with your specific setup.

[@ButImFeelingMuchBetterNow]

Hardware is old. Appprox 8 year old desktop. AMD FX 6300 8 GB ram. Running KDE on Manjaro.

[@quantumtacos]

Disable any of the multitude of krunner plugins you don't need, especially file search. It still won't be instant, but for me that has always made it usable.

[@roknauta3469]

Sensacional, diversas configurações legais e úteis. Parabéns.

[@zeniktorres4320]

Cheers!. Being a recent switcher from gnome, I didn't know about some of these.

[@Daniel-wn5ye]

I learned recently that you can customize the desktop contextual (right-click) menu to enable / disable items for it. And to make it really short and to the point, you can right-click after left-click and holding left click.

[@puspamadak]

KDE Plasma is the most complete desktop experience in the Linux world. I knew everything you showed in the video, except for the minimal application menu on mouse click. I can finally ditch the large application menu in the panel. Regarding changing the window opacity, you can bind it to Super+mouse wheel (if you have a wheel in mouse) from settings -> window management -> window actions.

[@crazycatman4171]

Thank you for your video. Transparency by keyboard shortcut was indeed new for me. I think it is important that you announce the KDE Plasma version you use at the beginning of your videos (I presume it was >= 5.21), because one or two of the features you mentioned might not work in older versions.

[@michael_tunnell]

That is a great point! You are correct the Super key window move and resize requires a specific version. I will make note of it for future videos. Thanks!

[@jonglass]

I used to run 9 desktops, arranged in a 3x3 grid. My main desktop was in the very center of the grid. My two next most important were right next to it on the middle row, and the next two above and below the center desktop. In the corners, I had items I kept open for reference (translation/definition apps, calculator, etc. I believe this was KDE on Mandriva. I liked it so much, I found a tool to do the same on the MacOS. And then, later, I moved on and forgot about it. Your video reminded me I did that, and now... I want it back. ;-) Don't need it any more, but I want it! :-D Edit: I forgot to mention that this was on a netbook with a 10" screen, where a cluttered desktop was a huge productivity killer.

[@michael_tunnell]

Thank you for commenting, 3x3 certainly has some advantages that I forgot about. Thanks for reminding me. :)

[@w01dnick]

I have 9 virtual desktops (3x3). For a long time. It's just more comfortable to have apps spatially placed than just bunch of apps on one-two desktops. Also when switching between desktops whole layout on both of my screens is switched instead of just one active window.

[@michael_tunnell]

Thank you for commenting, 3x3 certainly has some advantages that I forgot about. Thanks for reminding me. :)

[@abbasqamar5397]

Thanks you for the excellent tips.

[@homermakes]

I didnt know like all of these. thanks

[@Anonymous4045]

The kde store is one of, if not the best thing kde has to offer imo. If you've ever thought something along the lines of "why can't I do {insert feature here}, there's probably a script or theme or widget in the kde store that does it

[@johnmal5975]

Meta right click is the best! Thank you.

[@michael_tunnell]

you're welcome! I love that feature as well :D

[@brennandoherty1778]

A lot of great tips in here! Thanks! Liking the smash button on this one

[@michael_tunnell]

Thank you very much! I'm glad you enjoyed it!

[@stephanep7103]

Bonjour, Un petit commentaire en français pour vous remercier pour vos vidéos ludiques. Merci également pour votre diction claire rendant les sous-titres parfaitement compréhensibles. Excellente continuation :)

[@michael_tunnell]

I translated this online and provided that the translation is accurate . . . thank you very much for your kind words! :D

[@stephanep7103]

@@michael_tunnell The most difficult thing is to find the equivalent of your channel in French! Unfortunately, finding one that is qualitative, interesting, affordable, is difficult! See you soon;)

[@AndyGait]

A few useful things here. Thank you. Liked and sub.

[@gnm280]

That was super useful. Thanks.

[@df3yt]

I've used KDE for years... And learnt some cool shortcuts here, thanks for increasing my productivity! The store is another awesome feature that makes KDE way better than other DEs, no need to nav to sites, download and install. Plus I love it's daily wallpapers. All builtin. No 3rd party extras like variety needed. Plus different wallpapers per screen and VD. Ps you should cover Activities Vs desktops.

[@Prophet6000]

Thanks to this video I now use Krunner it is great.

[@michael_tunnell]

Nice! I'm glad it was useful

[@marcuswest4572]

Top tier tips. Thanks

[@Ma1ne2]

This video is super helpful! Thanks to telling me about the zoom feature, I could finally combine that with touché (touchégg) to get a pinch zoom on my laptop how I learned to love it on windows. Even better, it doesn`t just work in the browser, but in every window. Showing me again that on Linux, everything is possible, if you know how. (I switched to Linux about 3 months ago from Windows)

[@l__________________3452]

Btw you can start typing the application name in the present windows view and press enter or click on a window to switch to it and the virtual Desktop it is on.

[@GustavoKureckPiccoli]

Thanks for share knowledge!

[@dorktales254]

Ctrl+F10 seems like an awfully gymnastic move for such a continent feature

[@jaymandell6034]

I found a few of these by accident but you blew my mind with the others. I've seen a few kde customization videos that show transparent system menus but I'm still struggling to figure out how they did it. 🤔

[@michael_tunnell]

The transparent menus is built into the latest versions of KDE Plasma but there's also something else that might be what they could be using, Kvantum.

[@antonpodkur3520]

Thanks for such a useful video!

[@michael_tunnell]

You're welcome, I'm glad you found it helpful!

[@cenedi]

Many thanks for this video. The quarter tiling and shortcut to hide window border was new to me. Has anyone tried the "konsave" tool to save/apply Plasma customizations? I'm curious how well it works. My usecase would be the automated setup of lab machines.

[@michael_tunnell]

I haven't tried it yet but I have been meaning to do so. I might give it a shot soon just for the sake of it.

[@ayushmaanraturi]

I Loved your video and I am a bit amazed that KDE has this much features. Can you please tell me whether these keyboard shortcuts you used in your video are available for all KDE using OS or these are only available in Fedora KDE spin?

[@michael_tunnell]

I'm glad you enjoyed it! The shortcuts depend on the version of Plasma available but not the distros. Some distros ship older versions of Plasma and so it wouldn't have some features. With that said, as long as they have the latest version of KDE Plasma then they will all have the same shortcuts and features available.

[@محمدفرج-ث7ذ3د]

It was very usefull video thanks

[@WyvernDotRed]

I knew of literally all these features but criminally underuse them. But when I need them, they are there. Often a situation comes up where such a small feature can save you. Also in other DEs. Like having bugged panels (on XFCE) from connecting a different monitor, but still being able to launch everything from the desktop.

[@alternatuber6698]

You'll forget some of them and will search for this video and come back :D

[@michael_tunnell]

Well to make that easier, id suggest subscribing. 😃

[@quinten01]

Very useful video thanks!

[@michael_tunnell]

You're welcome, I'm glad you enjoyed it

[@priit7777]

Only feature I didn't know/remember nor use therefor was the disappearing of borders. Everything else was like common knowledge from the second day I swapped to linux from windows like 2 years ago... just because it was rather confusing and I literally took a day to go through every single setting in the KDE settings to see whats even possible to customize. :D

[@michael_tunnell]

That's pretty much what I did as well when I switched to Plasma. I just went through basically everything . . . It's like a blackhole that sucks you in lol

[@miketills4524]

Another outstanding video Michael. Every time I consider jumping to another DE I just can't get myself to do it. What Linux distro are you running? I am on fedora 34 and has been great.

[@michael_tunnell]

I have tried various DEs randomly just to see if Plasma gets a challenger at some point. So far there are at times things I wish Plasma could do based on those tests but still every time there's always a ton more that only Plasma can do so it's easily the undisputed champion of my desktop. :)

[@sheikhshakilakhtar6844]

Thanks Michael This was a good video

[@michael_tunnell]

You're welcome and thank you for the kind words!

[@thingsiplay]

Who wants a TuxDigital video at 3 A.M.?! Oh boy! 3 A.M.! NOM NOM NOM great content NOM

[@StephenSE9]

There's a new keyboard shortcut in Kdenlive. The "=". This jumps the cursor to the time-code of the selected monitor: Clip or Project.

[@jesse7631]

Very good tips! Here's a hidden gem in KDE I would like to find - how to apply wallpaper to both monitors all at once. KDE acts like each monitor is another computer that it doesn't even know exists! That is annoying.

[@michael_tunnell]

in theory if you add this menu option in Dolphin it would do it. but I have not tried it so I cant promise anything for it. store.kde.org/p/1169583/

[@snowhusk]

Mod+LMB to move and mod+RMB to resize is a feature that I like in i3 (daily driver for 2+ years now) and I like that this feature is kinda like an expected second nature in DEs now. Thinking of switching distro and de, and KDE Plasma looks sweet as hell

[@aaaaaaa1]

"The 'Pager' widget is handy, it allows you to move applications between desktops by simply dragging their icons from one desktop to another all from the current desktop. After adding the 'Pager' widget to your taskbar, configure it to show application icons.

[@scheimong]

Super+Mouse is a real game changer. Combined with Alt+F3 and your Super+B shortcut, there is basically no reason to keep the window frame around anymore.

[@LorenzoBettini]

Nice video! I think you forgot to mention another cool feature when in "Present Windows": just start typing, e.g., the name of an application of a string of a titlebar, and the overview is filtered accordingly, so that you can simply start typing to activate one of the many windows you have :)

[@michael_tunnell]

This is a good one. There are so many that I had to limit how much I covered otherwise it would be a super long video 😃

[@diegonayalazo]

Thanks for sharing

[@Rob-cq1nf]

omg. your video convinced me to switch to kde after strict 9 years of gnome. another reason is the annoying topic of hidpi and gnome...but i will not leave fedora :). fortunately there is also the kde spin. thanks for the video ;)

[@michael_tunnell]

You're welcome and I'm glad you enjoyed it! Hidpi is another great reason 😎

[@VulcanOnWheels]

I would recommend that you change the title to 17 KDE Plasma Features That You *Probably* Didn't Know About. Other than that, I like your video.

[@manw3bttcks]

Why did they get rid of the "disable touchpad when mouse plugged in" feature?

[@JoeLinux2000]

Where can I get a Plasma or Linux sticker to cover the "Windows" super key?

[@ghsgz3011]

Your wallpaper is great, can u post a download link? Thanks!

[@michael_tunnell]

This is the default wallpaper of Fedora 34. I'll get you a link though

[@zecuse]

I use the Bismuth WM. Never thought to try it, but that super+LMB shortcut works with the touchscreen! Also for some reason (Bismuth maybe?), that Toggle Borders KWin script doesn't seem to work (I'm on EndeavourOS if it matters). I have to assign a shortcut to the Toggle Window Titlebar and Frame script and manually change windows.

[@_rolo_6683]

Thanks for this great video (and the others too)! I always a bit confused about the KDE Activities Feature and what can it be do better then normal virtual desktops. But maybe I missed that you already covered Activities in another video.

[@michael_tunnell]

I have not made a video on this before. I can say that its not really much different but the key difference is session saving. Activities are meant to save your place in apps but the issue is that they don't always do it right so I just don't use them

[@lawrencedoliveiro9104]

It’s like having a second dimension to the multiple desktops feature. A desktop is a collection of windows, while an activity is a collection of windows across all desktops. Or conversely, a desktop becomes a collection of windows across all activities.

[@rhrast]

Super super... your system is Fedora, right? Thanks a lot....

[@michael_tunnell]

Yes, I use Fedora as my daily driver distro

[@jeremydoerksen5988]

Great Video!

[@michael_tunnell]

Thank you very much

[@PlasticImaginationWorkshop]

great video, thanks. I really like KDE Plasma but I have one thing holding me back on my main PC. I have three monitors and I need the center one to switch between workspace's and the left and right one to NOT switch. I'm currently using Cinnamon and it works, I'd just rather find a way to accomplish this in KDE, any thoughts? Thanks again for the great video. Have a great day. -David

[@lol-hz9mc]

Thank You very much

[@michael_tunnell]

You're welcome :)

[@Golevbivskyi]

Very useful video as for me. I'm new to Linux world. Thanks to the author. I'd like to see more the videos like this.

[@michael_tunnell]

thank you very much! there are absolutely more videos like this planned 😎👍

[@phillipmeza3459]

Michael, I'm using Manjaro KDE 21.1 an issue... and a Question, The "Properties Window" is where I "edit" an icon to match the "any incomplete set for the panel" I'm using, in this case my "go to" ... Sardi Ghost Archway, Manjaro won't let me save my edit... any thoughts? This never happened before. I've searched YT & ARCH forums (not sure how to pose my question) for a solution, I've reached out to others for clues, nothing as-of-this-message. Thank's Phillip

[@BA-ix4my]

Hello, thanks for your video. It was so useful. Is there a way to set the drag and drop file to move only in KDE? Dragging a file opens a menu and asks three options, move, copy, and link. Although it is possible moving with shift key I would like to do it just by dragging without having the menu shown as in Windows. If you know the source code directory please share it with me, as well. Thanks from now on!

[@michael_tunnell]

I looked to see if I could find a setting to do this and unfortunately I don’t think it’s possible in the gui. It is probably possible by changing a configuration somewhere but I’m not sure how to do that.

[@leonny03]

thanks man you best user i like this type video thanks a lot man.

[@axtrifonov]

Can i somehow decrease saturation of particular window in KDE? I often play with ZX Spectrum emulators, and ZX Spectrum palette is too vivid for my eyes.

[@phillipmeza3459]

Michael, I realized I chose the wrong place to ask a question... but found the "answer" from a video you posted in March, 2016 "Plasma 5 Application Widgets and Managing Your Applications with KDE Menu Edit" I've been "editing" panel icons the hard way and sometimes with a "negative" effect! I asked for help from the Manjaro Forum earlier today and STILL been denied, but I know that if you continue to pursue, you'll find what you need!!! The "KDE Menu editor" solved my problems! why... why.... is it hidden? Phillip

[@michael_tunnell]

Sometimes things are just hard to discover unfortunately. I'm glad my video was able to help though 😎👍

[@Cipricus]

All shortcuts are themselves customizable. The window manager is the biggest part of a desktop and Kwin cannot be compared to other window managers (there also, everything can be controlled by shortcuts). Window buttons (controls) size can be changed too. And then there are the windows rules that you don't have to use if you don't want to, but you can.

[@sharafat-karim]

Thanks man! But i lost my kde setting. I forgot how to set default input language 😭.

[@michael_tunnell]

oh losing settings is never good, sorry to hear that. The default language is set at System Settings -> Regional Settings -> Language

[@peterthecoderd.1210]

I think Kvantum is a worthwhile upgrade if you love eye candy.

[@michael_tunnell]

Agreed, Kvantum is very very cool

[@solasoul33]

Thank you

[@michael_tunnell]

You're welcome 👍

[@Uzvern]

Супер! Спасибо за ресайз. Не знал🔥

[@jasonblankenship4418]

after i set all my custom keyboard shortcuts and window behavior, is there a file that all is this exports to ? it would be neat to then drop this file into any other system with plasma and have all my stuff the way i like it rather than manually setting everything on all my computers.

[@michael_tunnell]

There should be but unfortunately no. The files are stored in your .config folder on your /home folder but there's a lot of them. You could try the software "Konsave" which is made for backing up KDE settings but I've never tried it so I don't know how well it works

[@AbdellahIdazzi]

Awesome!

[@ryanb6503]

My cat walked across my keyboard and somehow pasted my clipboard as a sticky note. KDE is full of wonders

[@SomeTechGuy666]

Good video. What is the equivalent of the Superkey on a non Windows keyboard ? I have the "plain" Logitech Master MX. It has a CMD button, but I can't see to make it work. KDE rocks ! I can't believe that people choose Windows over Linux/KDE. SMH.

[@michael_tunnell]

It sounds like you have a Mac style keyboard and for those you may need to remap it to Super though I'm not sure if that's actually possible or not. There is an advanced configuration thing in the Input section of System Settings that might have converging like that

[@babyboomertwerkteam5662]

Command is the super key on Mac keyboards!

[@SomeTechGuy666]

@@babyboomertwerkteam5662 Thanks

[@YannMetalhead]

Good video.

[@michael_tunnell]

Thanks! I'm glad you enjoyed this one as well! 😎👍

[@nymusicman]

Only problem with this video is it's not Super+Left/Right click, but it's Alt+Left/Right click for those commands. Alt+Left for window movement has been part of the linux desktop (KDE, GNOME, etc...) for as long as I've been using Linux on the Desktop (circa 2005). Also I can't remember if this is default or not but Alt+Scroll Wheel will do the window opacity lowering/raising.

[@w01dnick]

That default was changed some time ago. For me it's also still Alt (just used to it) but for new installation it would be Meta.

[@michael_tunnell]

As Mykola mentioned, it used to be Alt but they changed it to a Super a few releases ago. I recommend changing it to that in your install as well because the alt key isn't used up then. There are many apps that turns out uses alt and drag for stuff, many more than I realized until they changed to Super.