(fwGui): manage more gui aspects
What does this MR do?
- Manage label of SCamera.
- Remove a "pading" warning in flatdark.qss.
- Add tooltips on button in the WindowLevel.
- Change the color of disabled QLabel.
- Allow to set the size of each borders in layouts, and manage spacing between widget in the same layout.
- Fix the icons aliasing in the wizard.
- Fix the opacity in
fwGuiQt