Issue report: Steam dialogs and windows appear behind main window (KWin)
I am using KDE on Kubuntu 12.04. When I click a menu item that opens a new window such as View Friends List or Settings, the newly opened window is obscured by the main window.
Disabling KWin's focus stealing prevention feature (System Settings => Window Behavior => Window Behavior => Focus stealing prevention level) makes the problem go away (at least until I re-enable it to deal with some other less-user-friendly programs). I normally use the default setting (Low) and most applications, including those that have modal and modeless dialogs, do not have a problem with it.
For now, I have added a focus stealing exception for windows with the class "Steam".
I do not know all the details of KWin's focus stealing protection, but thanks to xwininfo and xprop I have discovered a potential issue: The Steam windows don't have the WM_CLIENT_LEADER and WM_TRANSIENT_FOR attributes that normally allow the window manager to know that they are related. According to some possibly unreliable forum/blog posts, WM_CLASS, _NET_WM_PID, WM_CLIENT_MACHINE must also match to make the focus stealing prevention work correctly.
Speed: 3301 Mhz
4 logical processors
4 physical processors
Operating System Version:
Ubuntu 12.04.1 LTS (64 bit)
Kernel Name: Linux
Kernel Version: 3.2.0-29-generic
X Server vendor: The X.Org Foundation
X Server release: 11103000
Driver: NVIDIA Corporation GeForce GTX 560 Ti/PCIe/SSE2
Driver Version: 4.3.0 NVIDIA 310.14
Desktop Color Depth: 24 bits per pixel
Monitor Refresh Rate: 59 Hz
Number of Monitors: 1
Number of Logical Video Cards: 1
Primary Display Resolution: 1920 x 1200
Desktop Resolution: 1920 x 1200
Primary Display Size: 20.39" x 12.76" (24.02" diag)
51.8cm x 32.4cm (61.0cm diag)
Primary Bus: PCI Express 16x
Primary VRAM: 1023 MB
Supported MSAA Modes: 2x 4x 8x 16x
RAM: 16027 Mb
UI Language: English
Microphone: Not set
Total Hard Disk Space Available: 9968 Mb
Largest Free Hard Disk Block: 8081 Mb
Recent Failure Reports: