[Development] QtQuickComponents ComboBox with QEglFSWindow

[Rutledge Shawn]

On 11 Apr 2014, at 10:15 PM, Matt Broadstone wrote:

> Hi,
> We're experiencing an odd crash while running our Qt Quick application in a VirtualBox session using eglfs on the framebuffer. The application works perfectly passing the '-platform eglfs' options, however, when we try to use a ComboBox we get a segfault/qFatal, with the resulting backtrace (only first twelve frames included for "brevity"): 
> 
> #0  0x00007eff7c041389 in raise () from /usr/lib/libc.so.6
> #1  0x00007eff7c042788 in abort () from /usr/lib/libc.so.6
> #2  0x00007eff7c956895 in qt_message_fatal (context=..., message=...) at global/qlogging.cpp:979
> #3  QMessageLogger::fatal (this=this at entry=0x7fff32b96030, msg=msg at entry=0x7eff7768e380 "EGLFS: OpenGL windows cannot be mixed with others.") at global/qlogging.cpp:384
> #4  0x00007eff7766cfb7 in QEglFSWindow::create (this=this at entry=0x1db8030) at qeglfswindow.cpp:115
> #5  0x00007eff7766b60e in QEglFSIntegration::createPlatformWindow (this=<optimized out>, window=0x1db66f0) at qeglfsintegration.cpp:122
> #6  0x00007eff7d03180b in QWindow::create (this=this at entry=0x1db66f0) at kernel/qwindow.cpp:480
> #7  0x00007eff7d032150 in QWindow::setVisible (this=0x1db66f0, visible=<optimized out>) at kernel/qwindow.cpp:426
> #8  0x00007eff6c888d6a in QQuickPopupWindow::show (this=this at entry=0x1db66f0) at qquickpopupwindow.cpp:95
> #9  0x00007eff6c888579 in QQuickMenuPopupWindow::show (this=0x1db66f0) at qquickmenupopupwindow.cpp:57
> #10 0x00007eff6c884efb in QQuickMenu::__popup (this=0x1bff2e0, x=<optimized out>, y=<optimized out>, atItemIndex=0) at qquickmenu.cpp:403
> #11 0x00007eff6c897f53 in QQuickMenu::qt_static_metacall (_o=_o at entry=0x1bff2e0, _c=_c at entry=QMetaObject::InvokeMetaMethod, _id=_id at entry=22, _a=_a at entry=0x7fff32b96550) at .moc/moc_qquickmenu_p.cpp:227
> #12 0x00007eff6c898427 in QQuickMenu::qt_metacall (this=0x1bff2e0, _c=QMetaObject::InvokeMetaMethod, _id=22, _a=0x7fff32b96550) at .moc/moc_qquickmenu_p.cpp:330
> 
> There is some mention on the i.MX6 wiki page about multiple windows (http://qt-project.org/wiki/i.MX-6), but that appears to be related to mixing Quick views and widgets, which we are not doing. There also seems to be an existing ComboBox bug (https://bugreports.qt-project.org/browse/QTBUG-35989), but this looks like it's quite different. 
> 
> Any insight would be appreciated, I just wanted to do some further investigation here before creating the bug report.

What version do you have?  Looks like the combo box is trying to create another window for the dropdown list, and we're not allowed to have more than one window on eglfs.  I don't think it should be doing that anymore on platforms where it's not supported.