Both tabbars will now have the same height.
This commit fixes incorrect drawing of line under pinned tabs when
moving tabs with Oxygen theme.
Also removed unused maxVisiblePinnedTabs property
Set of patches:
Introduce TabStackedWidget+ComboTabbar
[Windows] Fix enabling blur background in fullscreen
[ComboTabBar] Fix some issues with pinned tabs
[ComboTabBar] Don't use pointer to integer,
Implement TabStackedWidget::keyPressEvent() and fix changing tab by wheel event
Fix animation delay of dragged tab's buttons.
[ComboTabBar] Add themable scrollButtons