Although it is a good idea, which "window" do you mean: the output "window" normally at bottom of the UltraEdit window or the "List lines containing find string:" "window"?
I'm not a Windows programmer, but I know that both are not real windows like a document window. And I know that there are big differences between a document window object, a list view object (= output window) and a resizeable dialog object (= list lines...). I have never seen a program which has displayed colored text in a list view or a multi-line area in a dialog.
Maybe what I have written here is nonsense, but I would not be too optimistic to get syntax highlighting ever for search results in one of these 2 "windows".
If you mean the document window ** Find Results **
created when running a Find In Files with output to an edit window then you can already syntax highlight it. Just use View - View As (Highlighting File Type) - ???
. Since UES v6.10 and UE v12.20 at Configuration - Editor Display - Syntax Highlighting
the setting Highlight new files as
can be used to define a syntax highlighting language for new files which is used also for the ** Find Results **
document window. Users with an older version of UE/UES could use the default syntax highlighting feature described at syntax highlighting on a new file