Application Window not following "Window Rules"

[bobcal2000]

I am new to Kubuntu, this is my first post and and I’m trying to setup my system. I used the support template as best as I know how. If you need any of info, please let me know. Thanks in advance!

Ubuntu Support Template

Ubuntu Version:
Kunbuntu 25.10

Desktop Environment (if applicable):
KDE Plasma 6.4.5.

Problem Description:
Windows Rules -

1 - A side note first while I reading other posts for issues with Window Rules my screens to create window rules are not the same as every post and DuckDuckGo AI search I’ve done. Not sure why but I figured out how to accomplish the same thing as the posts are doing with the screens available in my “System Settings | Windows Management | Window Rules”. The screen shot below is what my window rule looks like.

2 - The main issue is the app windows in this case dolphin doesn’t want to follow the rule and open on my secondary monitor. I have two screens and I’m trying to have Dolphin open on my right (non-primary screen). I have tried all the “force, apply initially, apply now, etc.” spelling of dolphin with caps,etc.

3 - The other big mystery is the screen number, what goes here? I’ve tried 0-3. Is 0 the primary?

Example:

Relevant System Information:
ubuntu Linux 25.10 - Questing Quokka - Linux Kernel 6.17 - KDE Plasma 6.4.5 - Graphics Platform: Wayland
Hardware
ASUS PRIME Z590-P
Intel Core i9-11900K
64GB RAM
EVGA NVIDIA GeForce RTX 3060 Ti
Linux Driver: 580.95.05
2 Monitors - Primary Monitor (Left) - DisplayPort Connected / Secondary Monitor (Right) - HDMI Connected

[halogen2]

Is your Plasma session Wayland or X11? If X11 you can determine the window class for that Dolphin window by following the instructions here:

Is there any logging of how the system decides to treat .desktop files?

This requires setting the correct StartupWMClass=... line in the .desktop file. Unfortunately I forget how exactly to figure out what to put for the ... but I think the method I used before was something like: with the application open, run this in Terminal xprop | grep -P -i 'wm.?class' … then click the application’s window and look at the output? I think this won’t work in Wayland though

[bobcal2000]

Thanks for the reply! I am running Wayland only, no x11. Does this help or hurt me?

[bobcal2000]

Halogen2 - I read that post, that is for GNome, I’m running Plazma. I’m going to try upgrading to Plazma 6.5 to see if that helps.

Any thoughts?

[hdd-gehrke]

After doing a bit of searching I found this discussion on reddit: https://www.reddit.com/r/kde/comments/1c447nc/anything_like_xprop_in_wayland_to_get_window/ .
Seems like it might help …

[bobcal2000]

HDD-Gehrke

That link and something I learned yesterday reading another link, made it work.

From the link you gave me - click “Detect Window Properties” in the rule and then point and click on the application window you are trying to rule and it gives you all the window information you need (and transfers it to your rule).

From what I learn yesterday - Seems “window rules” don’t know about multi-monitors (at least that is what I surmise). If you have two monitors each at 1024x768 resolution the window rule sees one monitor at 2096x768 resolution. so the start position of 1025x1 is the upper left corner of the second monitor. This may or not be correct but it seems to work like that. If I’m wrong please someone correct me.

As for the screen property - this doesn’t do anything I can see, the screen number is not connected to anything I can see. Except for a future time when window rules can understand multi-monitor setups, this does nothing. If I’m wrong please someone correct me.

Thanks for your help!
Bobby