UI currently does not make it clear that "Contour" and "Texture" layer styles are only applied to canvas when "Bevel and Emboss" is active.
Changes in commit:
Disable "Contour" and "Texture" by default and re-enables them when "Bevel and Emboss" is applied.
Add code comments to clarify feature for other devs
WIP: Layer Style panel must be closed and re-opened for sub-style toggle to be visible/take effect.