UI: Anchor Right When Double-Clicking Last Word

In UI text inputs, when double-clicking to select words, anchor (set
initial selection position) to the right if on the last word. This
aids in some combined double-click-drag operations.

Pull Request: https://projects.blender.org/blender/blender/pulls/113125

source/blender/editors/interface/interface_handlers.cc

@@ -3803,7 +3803,8 @@ static void ui_do_but_textedit(
         but->pos = short(selend);
         but->selsta = short(selsta);
         but->selend = short(selend);
-        data->sel_pos_init = selsta;
+        /* Anchor selection to the left side unless the last word. */
+        data->sel_pos_init = ((selend == strlen(data->str)) && (selsta != 0)) ? selend : selsta;
         retval = WM_UI_HANDLER_BREAK;
         changed = true;
       }