bug with seek bar

[llansing]

After I loaded in a video, when I click anywhere in the seek bar, it didn't jump to the clicked position or go to the next key frame, instead it did nothing.  And once I'm not in the first frame,  mouse scrolling and clicking on the seek bar can only move the time backward.

[ajschult]

I seem to encounter a couple problems here.  The first is that the slider takes a tiny step when you click (at least in terms of avidemux's expectations).  The default value for pageStep (http://qt-project.org/doc/qt-4.8/qabstractslider.html#pageStep-prop) is 10 while I seem to need to set it to 100 million for anything to happen in the video I'm testing.  The second is that avidemux seems to lose something to roundoff somewhere so that it thinks the current slider position is actually a bit to the left of where it really is and so when it re-seeks, it concludes that it should go backwards. 

Anyway, pageStep is easy enough to hardcode in ADM_Qslider, but I suspect that the actual effect would be to try to jump some percentage of the total length, which may or may not do something useful or expected in many cases.  This may need a more dramatic change to explicitly handle clicking to either move forward/back by a key frame or to try to seek to the position that someone clicks on.