so if i change PPA to another with geany 1.33 compiled with gtk2 it would be work or not?
If it's built against GTK+ 2, it would work just as it did before.
Or how can i enable my old theme with gtk3?
You would have to port it to [GTK+ 3 CSS](https://developer.gnome.org/gtk3/stable/chap-css-overview.html). Unfortunately they changed just about everything between v2 and v3 to do with theming, but if you know CSS already, you'd probably find it easier/better in GTK+3.