Created attachment 107959 [details]
Screenshot demonstrating the cluttered visuals
The "Highlight windows" option of the task manager is supposed to present the user a preview of a window when hovering the mouse cursor on the window's icon in the task manager widget. This is working well for the window lying on top of all other windows: it is raised and the other windows turn translucent while the user hovers the top window's icon.
If the user, however, points his cursor on a window which is covered by other window(s), the covering window(s) turn translucent, but since they remain partially visible, the readability of the selected window is impaired. This might not be a problem for two or three windows, but when opening e.g. six pdf files the visuals become so cluttered that one cannot even recognize which window is currently selected, let alone reading the window content.
Steps to reproduce:
1) Right-click the task manager widget, select settings -> General and tick "Highlight windows".
2) Open about 6--10 windows, ideally with different content, e.g. pdf files, jpegs, etc.
3) Arrange them such that most of the windows overlap.
4) Hover the cursor over different application icons in the task manger. The selected window will be shown, but covering windows will be displayed in a translucent manner and impair the selected window's readability.
When hovering a window, it should -- temporary, while the user keeps hovering -- be raised to the top. No translucent windows should be drawn on top of it. The translucency effect may still be used for the areas not covered by the hovered window.
Basically, it's possible for the highlighted window to not get moved to the front, and then it gets covered by the other now-transparent windows.
There's a TODO in the code for exactly that
// TODO: We cannot just simply elevate the window as this will elevate it over
// Plasma tooltips and other such windows as well
//effects->setElevatedWindow( foundWin, true );
*** This bug has been marked as a duplicate of bug 298487 ***