Able to edit non-related Control node

[imjp94]

Font Family, Font Color & Highlight Color are always active regardless of whether selected Control node has font, font color & bg color property.

Assigning font, font color & highlight color doesn't raise any error, nor will the assigned object be saved to scene file(.scn/.tscn), but the assigned object will be added to undo/redo stack.

[MadFlyFish]

great