Review Request: Fix panel redraw after screen resize

[Ralf Jung]

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This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/106519/
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(Updated Sept. 21, 2012, 12:36 p.m.)


Review request for Plasma.


Changes
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Re-draw the panel explicitly only after a screen resize, not after each panel resize. I hope this also works for panels being moved onto another screen - I don't have an external screen here to test.

Interesting enough, I tried to do the same in DesktopView, and it did not fix the stale panel being displayed on the background. Either the redraw call must be made more explicit, or that "leftover" panel is actually a KWin glitch.

> i wonder if there isn't a race condition somewhere between screen resizing, panel window resizing and x events somewhere ...
I know little about the X and KWin internals, but the glitches are reproducible on two of my machines, with two different graphics drivers (fglrx and nvidia). From your reactions (and the existence of this bug) I conclude that most KDE devs are not affected... if there is any way I could help debugging this, please let me know.


Description
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This patch is my attempt to fix redrawing the panel when the screen is resized. During my experiments, I added update() calls to all places I could think of, but none of them helped - it seems that even though the panel is redrawn, that content is not properly displayed. I am not sure whether this might actually be a bug in KWin: For example, I also saw parts of the panel content end up in the desktop background if compositing was disabled and the background was set to a solid black, opposed to an actual image. I don't have the knowledge to persuade that idea further though.
I found, however, a solution (or a work-around) to fix the panel bug. Is that acceptable?


This addresses bug 269635.
    http://bugs.kde.org/show_bug.cgi?id=269635


Diffs (updated)
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  plasma/desktop/shell/panelview.h d105509 
  plasma/desktop/shell/panelview.cpp 7713740 

Diff: http://git.reviewboard.kde.org/r/106519/diff/


Testing
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Re-sized the screen a few times (using xrandr) to verify that the graphical glitches after a resize are gone.


Thanks,

Ralf Jung

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