Stumped by Grid stretch setup.

[winkle98]

I've got a dialog that contains two splitters. Everything looks okay and for the most part behaves as desired however, on the left side of the splitter (I've attached the .ui file)
I have a grid that contains various widgets. I've got a QListWidget that spans three columns of the grid and in the lower section several widgets with header labels. The problem is that if I stretch this area (whether by moving the splitter or stretching the dialog) I get a lot of margin space around all of the widgets. How do I stop this? I want the header label column to maintain a constant width and for the other widgets to expand and fill up their grid cell. When I set the stretch on a grid column it appears as though that column is stretching but the white space issue remains. (For example, the list Widget at the top does expand but there still lots of space on its left and right side. )

I've attached my .ui file since I think my explanation is a little confusing.

Any suggestions/help is appreciated.