Hi!
The XOTcl are scoped (or can be scoped) in object namespace too. I use it as follow
GUIClass instproc buildEntry win { my requireNamespace entry $win -textvariable [self]::entryValue my set entryValue {Init Value} } requireNamespace is required to build namespace for object. XOTcl object orientation is build (was build) on Tcl namespaces.
You have access to variable per my set userName or instvar userName set userName
I recommend also to use list command to programm callbacks
button $win -text "My Button" -command [list [self] buttonPressed]
Look at XOTclIDE http://www.xdobry.de/xotclIDE component (IDEBaseGUI) to have many examples how to bind XOTcl with Tk
Artur Trzewik