Version:           4.2.2 (using 4.2.2 (KDE 4.2.2), Kubuntu packages)
Compiler:          cc
OS:                Linux (i686) release 2.6.28-15-generic

Attempting to filter To-dos in the To-do list of Calendar by Category will not work if filtering by subcategory. Filtering by a category with subcategories should probably also show all To-dos with subcategories to that category, but it does not.

Steps to reproduce:
1. Create a To-do, name it anything.
2. Click the Category select button.
3. Click the Edit Categories button.
4. Select a Category and click the Add Subcategory button, name it anything.
5. Click Ok to close the Edit Categories dialog.
6. Select the new subcategory in the Select Categories dialog.
7. Click Ok to close the Select Categories dialog.
8. Click Ok to create the To-do.
9. Select the subcategory from the drop-down menu labeled Select Categories on the right.