tkinter.Variable class. They replace old methods trace_variable, trace,
trace_vdelete and trace_vinfo that use obsolete Tcl commands and might
not work in future versions of Tcl.
window is created for every test class.
Fixed Tkinter images copying operations in NoDefaultRoot mode.
Tcl command names generated for "after" callbacks now contains a name of
original function.
Tkinter.Variables; harmonize exceptions to ValueError; only delete variables
that have not been deleted; assert that variable names are strings
Patch by Andrew Svetlov.
