Visual glitches when changing application style from qlementine to a non-qlementine style

[IoeCmcomc]

Visual glitches appear in the sandbox example when the application style changes from QlementineStyle to a non-qlementine style (e.g. fusion or windowsvista) after the main window (SandboxWindow) is created.

How to reproduce:

1. In main.cpp file, comment out window->setCustomStyle(style);
2. In main.cpp file, put the following code after main window creation:

qApplication.setStyle("windowsvista"); // or qApplication.setStyle("fusion");
qApplication.setPalette(qApplication.style()->standardPalette()); // Force new style palette

4. Replace commented lines in the SandboxWindow constructor with the following code in SanboxWindow.cpp:

_impl->setupUI_button();
_impl->setupUI_buttonVariants();
_impl->setupUI_checkbox();
_impl->setupUI_radioButton();
_impl->setupUI_commandLinkButton();
_impl->setupUI_sliderAndProgressBar();
_impl->setupUI_spinBox();
_impl->setupUI_comboBox();
_impl->setupUI_toolButton();
_impl->setupUI_groupBox();

5. Compile and run the sandbox
6. Observe the issue

With fusion style

• Current behavior:
  
• Expected behavior:
  

With windowsvista style

• Current behavior:
  
• Expected behavior:
  

Note: Visual glitches don't occur when switching between fusion, Windows and windowsvista styles.

Debug information:

OS: Windows 11 23H2
Toolkit: Qt 5.15.2 MSVC2019 32-bit
Compile mode: Debug

[oclero]

Thank you. I haven't tried to switch between styles, so wasn't aware of this bug. I'll take a look when I have time