If you change the line:
You get rid of the gray background and the text field is positioned correctly. There are still a couple problems:
1. The spectrum has a gap on the far right. It is just too small horizontally for the scale of the spectrum box.
2. The spectrum does not appear to be vertically scaled (same physical height as the 3.2 screen)
3. Cosmetically, there is a gap in the upper left corner of the box that encloses the spectrum.
4. The sample rate of the frequency is probably too fast. Too fix, you have to slow the timer interval way down and then the spectrum lags in its update. Probably just leave it at the existing rate...
5. Not sure whether it is a problem or not, but on the 5" you get definite histrograms on the spectrum while on the 3.2 it looks like a more contiuous graph. Suspect that this is one of those things where having more resolution doesn't help. :-)
I am going to spend time on 1-3 and ignore 4-5. Any pointers there would be appreciated.