Fix Popup UI

[Neuffexx]

Now that new UI Widget implementation exists, and new colour parameters are passed, some layouts/colour spacing issues occur in Popup windows.

• Colour padding/margin space between widgets
• Fix some layout issues creating whitespace between some widgets where it shouldn't
  (ensure layout is the way it should be, may require restructuring some popup class's UI)

[Neuffexx]

Some pop-up's that need to be looked at:

• Any of the Preset Editing ones
• DragNDrop error handling (such as dragging a folder onto an image input)