For those who care about blur, here is all the info you can get.
Window decorations only
You want the terminal to be blurry from top to bottom for example. In this case, you will need to find some window decorations that are transparent. Obviously, you need to make sure the blur is enabled under desktop effects.I don't even use window decorations so can't really recommend a theme for you (achieved that by going to
Window body transparency
Install Kvantum from Kvantum github. Change to the Kvantum widget style in the → → . Then you can choose a Kvantum theme in the separate application called Manager Kvantum.
To get blur install some Kvantum theme with transparency like Materia Blur or Kvglass and choose that as your current theme. More so, to edit the themes you can, for example, edit the materia colors with something like this:
sudo sed -i 's/#4285f4/#3daee9/g' MateriaBlur.kvconfig sudo sed -i 's/#4285f4/#3daee9/g' MateriaBlur.svg
which will replace the normal color with the Breeze blue. You can do this by also opening a text editor and replace the color as you would normally do.
Keep breeze style
There is no need to install Kvantum.
Create a transparency Kwin rule by Alt+F3 → → , then in the dropdown menu for Window Class and Role choose Unimportant instead. Also select all window types, besides Desktop and Splash Screen. Thus, the will apply to everything. FORCE the active or inactive opacity to how much you want in the very last tab under . The end result will look like so and can be imported by saving it as .kwinrule.
[Transparent all the things] Description=Transparent all the things clientmachine=localhost clientmachinematch=0 opacityactive=90 opacityactiverule=2 opacityinactive=80 opacityinactiverule=2 types=445 wmclass=audacious wmclasscomplete=false wmclassmatch=0
Create another rule on top of the first that will be an exclusion rule. Separate window titles with |. So for ex conky|pqiv|plasmashell|something should be placed in the Window Class while having Regexp instead of Unimportant. For this one force the opacity to 100%. In case you don't know what window class something has (tho it is usually in the titlebar) you can press ALT+F3 → → and get the window class or when you create a rule there is a button that will let you click on something to get its properties (detect window properties).The end result will look like so, and can be imported by saving it as .kwinrule.
[Transparency exceptions] Description=Transparency exceptions opacityactive=100 opacityactiverule=2 opacityinactive=100 opacityinactiverule=2 wmclass=conky|pqiv|plasmashell|rpcs3 wmclasscomplete=false wmclassmatch=3
Install the Kwin script force blur and give it all the windows you want to have blur. Before that the command you need to run are the following. After this a setting icon will appear for Force Blur under .
mkdir -p ~/.local/share/kservices5/ cp ~/.local/share/kwin/scripts/forceblur/metadata.desktop ~/.local/share/kservices5/forceblur.desktop
So pretty much everything under .local/share/applications and /usr/share/applications can be added alternatively you can have a script like this and have it runs at startup. The force blur thing does the same thing.
if [[ $(ps --no-header -p $PPID -o comm) =~ '^yakuake|dolphin$' ]]; then for wid in $(xdotool search --pid $PPID); do xprop -f _KDE_NET_WM_BLUR_BEHIND_REGION 32c -set _KDE_NET_WM_BLUR_BEHIND_REGION 0 -id $wid; done fi