I am writing an editor using Scintilla.
I am already using a lexer to do automatic syntax highlighting but now I'd like to mark search results. If I want to mark only one hit I can set the selection there but I'd like to mark (e.g. with yellow background) all the hits.
I writing this in Perl but if you have suggestions in other languages that would be cool as well.
The "sample" editor scite uses the bookmark feature to bookmark all the lines that match the search result.
Have you read the Markers reference in Scintilla doc? This reference can be a bit obscure, so I advise to take a look at the source code of SciTE as well. This text editor was originally a testbed for Scintilla. It grown to a full fledged editor, but it is still a good implementation reference for all things Scintilla.
In our particular case, there is a Mark All button in the Find dialog. You can find its implementation in SciTEBase::MarkAll() method. This method only loops on search results (until it loops on the first search result, if any) and puts a bookmark on the found lines (and optionally set an indicator on the found items). The found line is gotten using SCI_LINEFROMPOSITION(posFound), the bookmark is just a call to SCI_MARKERADD(lineno, markerBookmark). Note that the mark can be symbol in a margin, or if not associated to a margin, it will highlight the whole line.
HTH.