Popup window appears hidden behind main window

I am running CAE linux in Virtualbox on a Windows 8.1 host.
popup windows appear behind main application windows, e.g.

trying to follow the piston example

Starting Salome, go to geometry, new,
File import --> popup window appears behind blue canvas.

similar popup behavior in Elmer.

Any ideas, how to solve the issue

Thanks WJ

claws: Thanks for the response.

I assume that no kde is acitive.

From the Top level Drop Down menu the following is active

System -> Settings -> Window Manager

Tab Focus
Click to focus: activated
New window focus: activated
Raise on focus: checked
Raise on click: checked
Tab Advanced
Snap windows to screen border: checked
Snap windows to other windows: unchecked

System -> Settings -> Window Manager Tweaks

Tab Focus
Activate stealing prevention: checked
Honor standard ICCCM focus hint: checked
Bring window on current workspace: activated

System -> Settings -> Session and Startup

Tab Advanced
Launch GNOME services on startup: unchecked
Launch KDE services on startup: checked

I cannot find a menu item to configue KDE settings, settings for desktop does not include Windows behavior

So far problem is still unsolved

Any ideas welcome.

Regards wj

My issue with the window is solved.

I started CAE Linux directly from Virtualbox, and shutdown Linux when I wanted to sign out. Yesterday I only logged out and found in the screen a dropdown where I could chose between Xubuntu and Xfce. Switching to xfce prior starting linux my window issue. After that, CAE Linux started without any issues.

Hope that will help some other people
Regards wj