I had also tried Ctrl-click in SciTE and that worked as expected.
What exactly is expected, I can't get Scite to do anything interesting on crtl+click. The version in my distro is kind of old (3.6.0) and maybe it was added after that.
How do you know it didn't work? IIUC multiple selections have a separate styling from the main selection, and since Geany doesn't set that style they may not be visible?