I've been following the instructions given here. Basically I just ran:
adb shell wm overscan 0,320,0,0
to fix a broken touchscreen issue on my Sony Z3 Xperia Compact with Android 6.0.1
Now some apps (e.g. Play store, the default Xperia Launcher and Spotify) seem to now reserve additional space where they don't place things. To illustrate my point, I attach a screenshot:
The black top third is what I wanted to have (because that's where the touchscreen doesn't respond). The middle third is what is added which I don't need. I'd rather use this space for the app I'm running, which is now entirely squeezed into the bottom third. As I said, this only applies to some apps.
Edit 1 I found some apps where this sometimes happens and sometimes not. This seems to be related to whether or they are trying to show a menu bar on top.
Edit 2 Gmail and google's Inbox have the same issue. Inbox even crashes.