Can't see Items List of QComboBox, when use showFullScreen

[Qingshui Kong]

Could somebody give me some help?

I have a question.

If I use showFullScreen in my Qt Widgets Application, I can't see the items list of all the QComboBoxes, when I click QComboBox.

My system information:

Windows 7, 64bit;
Qt 5.9.1

Compiler: MSVC2013 64bit

Did somebody meet this problem before. Could somebody give me some advices?
Thanks!

[AndyS]

This is a known limitation on Windows, I suggest you have a look at https://doc.qt.io/qt-5/windows-issues.html#fullscreen-opengl-based-windows as that describes the problem in more detail and gives a solution which you can use.

[mrjj]

Hi
That sounds really odd.
So the QComboBoxes are shown on screen but when you click to open the dropdown list, there is no items in it anymore?
No other widgets does strange things when showFullScreen is used ?

[Qingshui Kong]

@mrjj Hi
Thank you for replying so quickly!

Yes, it is very odd.

I find there is one more widget doing the strange things. It is QDateTimeEdit. It acts the same with QComboBox.

What's more, even though I can't see dropdown list, I can select one item by clicking.

[mrjj]

@Qingshui-Kong
Hi
Would be possible to test with newer/newest version of Qt ?

Also, did full screen work at some point but stopped or this is from beginning ?

Im wondering if it could be some sort of gfx driver issue or font rendering issue.

[Qingshui Kong]

@mrjj
Hi,

I haven't install newer version of Qt. So I can't test it now. Could you help to test that?

Full screen doesn't work. At least, I haven't seen that it works. So I think this is from the beginning.

If it is some sort of gfx driver issue or font rendering issue, how could I confirm it and how could I fix it?

Thanks!

[mrjj]

@Qingshui-Kong
hi
well i tested with
https://www.dropbox.com/s/3hlqg2hqm22m3gu/testfullscreen.zip?dl=0
and it works as expected.
Could You try same sample ?

Well you can check if any new drivers are available for your gfx card if not already done. ( like from Intel or nvidia)

[Qingshui Kong]

@mrjj
Hi,

Thank you very much!

This sample works.

Maybe, my program is a little complex. I should debug my program to find out the problem.

[mrjj]

@Qingshui-Kong
Hi
ok, that is good news. \o/
Its just a normal bug then.
Do you start app at once in full screen or
you toggle it ? ( like sample)

[Qingshui Kong]

@mrjj
Hi

I start app at once in full screen. I use w.showFullscreen() in the main() function.

[mrjj]

@Qingshui-Kong
hi
ok, i tried with sample that way too but still there are items.
So it seems its something in the real app code.
if you just do // w.showFullscreen()
then there is items visible ?
How do you fill the items to the combobox. any chance they can be empty strings for some reason ?

[Qingshui Kong]

@mrjj
Hi,
Yes, there should be some bugs in my app code.

If I use w.show() in the main function, it works.

I am sure that I have fill the items to the combobox. And I can select them by clicking, even though I can't see them.

[AndyS]

This is a known limitation on Windows, I suggest you have a look at https://doc.qt.io/qt-5/windows-issues.html#fullscreen-opengl-based-windows as that describes the problem in more detail and gives a solution which you can use.

[Qingshui Kong]

@AndyS

Thanks very much!

[Qingshui Kong]

@AndyS

Hi AndyS,

Could you answer my another question?
Here is the link.
https://forum.qt.io/topic/95431/how-to-set-window-flags-for-qfiledialog

Thanks.