Dear Chimera Dev Team, I am writing a Chimera extension and I use the Pmw toolkit in my GUI. I had no problems testing it and it worked great until I decided to reinstall my OS (Windows 7). After that, I installed Chimera 1.5.3, imported my extension and didn't face any problems at first. But then, after closing the viewer and running it again, an error occured right after importing the extension's gui: Traceback (most recent call last): File "<pyshell#5>", line 1, in <module> b=Pmw.EntryField(a,labelpos="w",label_text="asd") File "C:\Program Files (x86)\Chimera 1.5\bin\lib\site-packages\Pmw\Pmw_1_3\lib\PmwEntryField.py", line 73, in __init__ sequences = root.bind_class(tag) File "C:\Program Files (x86)\Chimera 1.5\bin\lib\lib-tk\Tkinter.py", line 1012, in bind_class return self._bind(('bind', className), sequence, func, add, 0) File "C:\Program Files (x86)\Chimera 1.5\bin\lib\lib-tk\Tkinter.py", line 947, in _bind return self.tk.splitlist(self.tk.call(what)) TclError: bad window path name ".94327912.94328912" I didn't change anything since the last succesful testing of my extension - something happened after closing Chimera for the first time, and I have no idea what it is. After that, I tried reinstalling Chimera, installing older versions - it's always the same story; everything works great on the first run, but after I close the viewer for the first time, I am not ever able to use Pmw anymore. The code that causes this error is simple: a=Tkinter.Tk() b=Pmw.EntryField(a,labelpos="w",labeltext="c") I tried to type the same thing in IDLE and I got the exact same error. Thank you for any help, best, Mateusz