When I want to filter my tasks according to categories it does not display the categories I have assigned to the tasks. The little window, which is popping up is flickering. I have attached a picture of this.
Categories are not displayed
You seem to have CSS turned off.
Please don't fill out this field.
Do you mean that the submenu "Categories" is not displayed? Which version of Task Coach are you using? And on what platform (Windows 7 I guess)?
Can you open a category viewer (View->New Viewer->Category) and attach a screenshot that shows the categories you have created?