Minimized windows shown as small rectangles

[midi-pascal]

Qt 4.8 and 5.4, Qt Creator 3.1 and 3.3.0 under Ubuntu 12.04

Since installation of Qt 5.4 and Qt Creator 3.3.0 my Qt apps show a defect.

If I minimize a subwindow of one MDI app, its corresponding "tab" that was showing previously at the bottom left of the main window with its icon and window tittle now shows as a tiny rectangle (I assume it is the tab few pixels wide):

Minimized.jpg

In this example there are 3 minimized subwindows so 3 tiny rectangles.
Even if I rebuild (qmake, clean and rebuild) with Qt Creator 3.1.2 using Qt 4.8 the defect remains.
I did not modified the code since the Qt/Qt Creator upgrade, only recompiled the app.
The small rectangle (tab) is active since the window menu can still be used by hovering the mouse curson on it and I can restore the window with it.

Any help on this would be welcome!

[wysota]

Does it work correctly if you build your program from the command line and not inside Qt Creator?

[midi-pascal]

Thanks for replying!

Nope.
After make clean and make on command line I get the same result.
I build the mdi Qt example to see what happens and minimized windows behave correctly.
Something in my app turned wrong at some point but I cannot see what could cause the problem.
This app is not a new project and used to work well until the upgrade.
Where is the code that displays the minimized tab?
I am ready to debug a lot but I do not know where to look at...

My subwindows inherit QDialog, are fixed size and I disabled maximize option with the window flags.
I tried to remove all the window options but the problem is the same

[wysota]

Thanks for replying!

Nope.

So why post your question in a forum related to Qt Tools and not Qt Programming?

Something in my app turned wrong at some point but I cannot see what could cause the problem.

Check your sizeHints and styles (and stylesheets).

My subwindows inherit QDialog

Hmm... why? It doesn't make much sense.

[midi-pascal]

Sorry.
Wrong place to post, and the problem was me.
I used wrong params to call addSubWindow() to the MdiArea.
The problems showed up now because the app was not recompiled for a while so I thought it was the Qt upgrade.
Shame on me, sorry.