I've experienced an auto-expanding Tcl/Tk-window:
(Windows NT)

import Tkinter
tk = Tkinter.Tk()
tk.state("zoomed") #Windows only
tk.resizable(False, False)
tk.mainloop()

As you take the window by curser and move it slowly to the left, it expands automatically to the right. This effect doesn't exist vertically.

When you use tk.state("zoomed") you needn't to set tk.resizable, but this call remained in my programm and caused that problem.

Systeminformation:
------------------
Windows NT
sys.api_version = 1012 #0x3f4
sys.dllhandle = 503316480 #0x1e0000
sys.getwindowsversion() -> (4, 0, 1381, 2, "Service Pack 1")
sys.hexversion = 33817328 #0x20402f0
sys.platform = "win32"
sys.version = "2.4.2 (#67, Sep 28 2005, 12:41:11) [MSC v.1310 32 bit (I
sys.version_info = (2, 4, 2, 'final', 0)
sys.winver = "2.4"
_tkinter.TCL_VERSION = 8.4
_tkinter.TK_VERSION = 8.4

Thanks.

Fabian Mareyen