Just a fast test ...
You can e.g. add a custum style by rightclick on the Edit1.
This will open Stylebook, with some automatic naming.
I usually use my own names, e.g. with starting "_", to easier find them again in that possible long list of styles.
Analyse the control, and add or change what you like.
E.g. you can add TRectangle in the style, as I did here.
Other controls may have direct access to colors, rectangles, etc.
With the added rectangle, you can add a specific name, here "background_rect", and you can find and access this as you wish.
! The Edit1.StyleLookup must of coarse now get the new style name "_myeditstyle", to switch to that.
I hope that helps to show one possible options howto customize the styles.
Rollo
T223_EditStyle.zip