Create a "Dead Mouse Area" control to eat mouse events underneath desired area. This is to prevent mouse events from leaking through controls underneath the area.
Replace original "NoMouseThroughRectangle" as this is more versatile.
Prevent mouse through events from leaking underneath the Fly View tool strip.

Added a bit more separation between the Toolstrip and the Toolbar

Increasing a bit the bottom margin for the confirmation dialogs
Changed the color for the guidedActionConfirm dialog to the palette’s alertColor
Disabled onHeightChanged on ToolStrip for the time being as it was not working. I need to come back to this and see why it hides “optional elements” even though I have plenty of space for them.
Adjusted the color for disabled text so you can read it within the ToolStrip

Previous mechanism was exposing possible bug in Qt which would prevent
clicks from work on ToolStrip buttons after cancel MouseArea was hidden.