Assign The Patch Assignment dialog will open when editing an OS and clicking the 'Assign Patches' button on the edit dialog. This dialog will allow you to manage the patches for the OS you're currently editing. The OS name you're editing patches for is displayed in the top toolbar in the dialog. The dialog supports the standard operations:

List View Patch List
When opening the dialog or clicking the list button you'll be presented with the list of patches currently installed in the OS. You can choose items from the list to edit or delete.
List Adding a Patch
The dialog is simple, it will allow you to choose from a list of predefined patches. (These are defined elsewhere). And also to specify install date for the chosen patch.
List Editing a Patch
The Edit dialog is similar to the Add dialog, and allows to change a current patch.
List Deleting a Patch
A patch can be deleted by chosing it from the list, then clicking the delete button. A confirmation dialog will popup to verify. The deletion will only effect the current OS you're editing.