As I Just checked it seems like its impossible to change the Start & End position of a HAP(Q) clip.
Checked with 1920x1200 15 sec File.
OSX Yosemite, Millumin 1.60
Same File as Photo-Jpeg Works Just Fine.
I don't remember it happening with older versions of millumin.
Comments
As I replied you a few days ago, HAP support in 64-bits is not yet recommanded, because it has been available to developer in this context too recently. We (all softwares) need experience on this topic.
The problem you are pointing out, is one of them.
Of course, this problem won't happen in 32-bits mode (HAP in this context have been widely used without trouble).
Best. Philippe