Tk version changes

[Robin Becker]

I have some tkinter code that used to work in 2.2, but is failing in
2.3. I guess it's because the Tcl version is different. Looking in the
text.tcl file I see that we now have ::tk::Priv and
::tk::TextClosestGap.

I can get this to work reasonably in 2.3.2, but how should I make this
kind of code version independent? Should I rely on the python version or
attempt to check which variables are present in Tk? If the latter does
anyone know which version of Tk this changed? 

        def _textB1(self,event):
                '''special binding for our disabled texts
                Allows dragging to select and copy, but not editing
                '''
                w, x, y = event.widget, event.x, event.y
                call = w.tk.call
                call('set','::tkPriv(selectMode)','char')
                call('set','::tkPriv(mouseMoved)',0)
                call('set','::tkPriv(pressX)',x)
                call('set','::tkPriv(pressX)',x)
                w.mark_set('insert',call('tkTextClosestGap',str(w),x,y))
                w.mark_set('anchor','insert')
                w.focus()
                w.tag_remove('sel','0.0','end')
                return 'break'

-- 
Robin Becker