The selection is maintained by Scintilla. Its *definition* of the selection is that it ends at the cursor. You can request Scintilla changes that, but it is unlikely to happen because it will break all Scintilla based editors.
Geany cannot change the behaviour until it is changed in Scintilla. --- Reply to this email directly or view it on GitHub: https://github.com/geany/geany/issues/816#issuecomment-164589657
