It is actually nice to have the filters in boolean combination but it is not obvious from the UI that the secelections are cobined (category gnome AND status=upgradable) 
It would be much more usable  (IMHO) if the user had visual feedback wich filters are active and could clean the filters with one click. 
Today if I select a filter, change the pane and select another filter often no packages are displayed, because none matches both. I have to remember which "filter-by" I selected, open the tab again, select "all".

Reproducible: Always

Steps to Reproduce:
1. Browsing packages by "Status" (left hand Filter pane) for instance "upgradable"
2. want to browse some other Filter tab (e.g.  By Category) and  _forget_ to select By Status->All before changing Filter  Tab 
3. Select filter Tab "By category"-> Debug
Actual Results:  
The result will be most likely empty since there are no upgradable packages in the debug category.

Expected Results:  
Select filter Tab "By category"-> Debug, will disable the filter "By Status"->upgradable 

OR  show that there are 2 active filter rules AND give the user a means to quickly deselect all prior filters.