Created attachment 1119708 [details]
Screenshots

Description of problem:

Welcome screen in Qt Creator is not drawn at all. The glitch seems to be only graphical - moving cursor over the black area reveals that some portions are clickable. Clicking them produces the expected dialog window.

Similarly parts of Design screen are not drawn if trying to edit Qt Quick application (please see attached screenshots). 

Version-Release number of selected component (if applicable):
qt-creator-3.6.0-1.fc22.x86_64

How reproducible:
always

Steps to Reproduce:
1. Click on the Welcome tab.

or

1. Create new project.
2. Select Qt Quick Application (and defaults on next steps).
3. Go to Design tab.

Actual results:
The selected tab is partly (Design) or completely (Welcome) blank.

Expected results:
The available demos should be shown in the Welcome tab, all controls should be shown in the Design tab.

Additional info:
When running qtcreator from command line, I get following outputs:

After startup (repeated about 20 times):
QOpenGLContext::swapBuffers() called with non-exposed window, behavior is undefined

After loading the projects:
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile

During new project creation:
"Error in \" .qtQuickVersion\": SyntaxError: Syntax error"
"Error in \" .qtQuickVersion\": SyntaxError: Syntax error"

First time I open Welcome tab:
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile

Each time I leave Design tab for another one:
QCoreApplication::postEvent: Unexpected null receiver
QCoreApplication::postEvent: Unexpected null receiver