Hi! My application (extension) works fine when execute it within the built-in IDLE. The python-code basically executes an external program (using "popen" ) and manages communication between the application and chimera through named pipes... (The external Application uses Qt and all my trials to smoothly integrate it by use of a python wrapper have failed...) Now I want to add an icon to chimera, which should call my extension in the same way I do it in the IDLE. I did not manage to get the ToolbarButtonPackage working: the related documentation seems to be completely outdated: ""The example code files and ToolbarButton.tiff must be saved in a directory named ToolbarButtonExtension. To run the example, start chimera, bring up the extension manager (via the Manager... entry in the Extensions menu), select the Directory tab, and Add the directory above the ToolbarButtonExtension directory. A MainChain entry should appear under the Utilities extension category."" Anyway, the ToolbarButtonExample works, but I can not adapt it to my application. When I add the path within the Favorites/Preferences/Tool - Tab chimera dies... I include the set of python files I use: Thanks for your help, Lars