It doesn’t affect the result but they are expected to be:
The quoted form working is an accident and could change behaviour in the future.
> When I perform a search it renders the selection in white text on a black background. I noticed that when I perform a replace and click on Find Next that this does not apply and it reverts back to a light-grey foreground.
There are more selection properties now. When the replace strip is opened, it gains the keyboard focus (so you can type some search text) and the edit pane loses focus, displaying its selection in ‘inactive’ colours.
Try setting the inactive selection colours like
This will show when selections are inactive with a green background.
After seeing the effect, you may then choose to use
If the desire is for always the same selection colours then there are also the secondary colours (like selection.secondary.back) which may occur. To see secondary colours, select some text in SciTE; open another application (like Firefox) and select some text in it; then activate SciTE without selecting text. The different colours indicates that SciTE has focus but does not control the primary selection so will not be the source for middle-mouse-button primary selection paste.