D7246: Tooltips

[Martin Flöser]

graesslin added a comment.


  In https://phabricator.kde.org/D7246#171908, @graesslin wrote:
  
  > I'm sorry, but Widgets is a dependency which cannot be used for it. This creates problems in KWin. Tooltip support must be implemented directly in KWin, exposed through the KDecoration API. Yes I know that makes it rather complex, but that's the reason why tooltip support wasn't added to KDecoration through QWidget in the first place.
  
  
  I thought a little bit more about it. It might be possible to use QWidgets if it's done inside KWin. That might work correctly. If it's not directly controlled by KWin, it's problematic and will most likely not work correctly. To explain: KWin has difficulties creating windows. I know it sounds stupid, that the window manager is not able to create windows, but that's how it is. KWin has to do quite some tricks and track windows internally. If a window gets created by a library loaded into KWin and KWin doesn't know about it, such internal tracking breaks. It now has a window it doesn't know about. That's especially a problem on Wayland, on X11 it works better for windows such as a tooltip.
  
  But long story short: for KWin the best is a request from KDecoration "showTooltip(const QString &)" and KWin creates the tooltip window, positions it and ensures it works correctly.

REPOSITORY
  R129 Window Decoration Library

REVISION DETAIL
  https://phabricator.kde.org/D7246

To: McPain, #breeze, #plasma, graesslin
Cc: ngraham, broulik, plasma-devel, #breeze, ZrenBot, progwolff, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, mart
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