Red Hat Bugzilla – Bug 830322
Black boxes around text boxes and buttons
Last modified: 2015-02-17 09:16:56 EST
Created attachment 590514 [details]
Image of the rendering bug
Description of problem:
When using the mingw32-webkitgtk package on Windows, often times black boxes will be displayed around text boxes and button widgets. Attached is a screenshot of the xombrero browser running on windows displaying this bug.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Download and install xombrero for windows (comes with rawhide webkitgtk) from this link: https://opensource.conformal.com/snapshots/xombrero/windows/
2. Open to the webpage in the attached screenshot (https://opensource.conformal.com/wiki/Main_Page)
webkitgtk tries to draw gtk widgets by using alpha compositing. gtk2 however doesn't support this very well (e.g. see the comment about Windows backend at http://developer.gnome.org/gdk/stable/GdkScreen.html#gdk-screen-get-rgba-colormap) and instead of transparency, we just get black colour.
This is certainly fixable, but unfortunately webkitgtk Windows backend isn't receiving much attention upstream, and the gtk2 support is also slowly getting phased out.
The issue is gone with gtk3, and I plan to do a mingw32-webkitgtk3 package that's built against gtk3 soon. Would that work for you?
See also the upstream report discussing the same issue:
Thanks for the quick response and finding the bug upstream. Unfortunately, switching to gtk3 at this time isn't really an option for us (it's a lot of work, and we want to make the gtk3 switch at the same time that the webkit2gtk api goes stable).
Also, another one of our devs has noticed that the openSUSE package does not have this rendering issue, so maybe they have worked out a solution. It would be great if this was also working with the rawhide package!
Link to the package: http://ftp5.gwdg.de/pub/opensuse/repositories/windows:/mingw:/win32/openSUSE_Factory/noarch/mingw32-libwebkitgtk-1.6.1-2.38.noarch.rpm
It's caused by the version difference. mingw32-webkitgtk-1.6.1-1.fc16 from Fedora 16 doesn't have this issue either.
webkitgtk has fallback code that tries to work around the missing alpha channel support, but unfortunately it's broken with 1.8. There was a big rendering rework and the gtk2 port now uses a cairo surface for backing store. Previously, when there was a GdkWindow associated, the fallback code simply drew directly on the GdkWindow. But now that the backing store is a cairo surface, it's not so simple any more with gtk2 (with gtk3 the cairo surface is a perfect fit).
This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.
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cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)
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