hi,
I'm running Avidemux 2.6.8 on Debian 8 Jessie with GNOME 3.14.1 on my netbook Dell Mini 9 (aka Inspiron 910) with its 8,9" WSVGA screen(1024*600 pixels)
I've noted that the main window is unusable with my screen since it's bigger than my screen and doesn't show scrollbar to vertically scroll into the window
see screenshot attached
Thanks
You should be able to reduce height of avidemux by pulling down top edge of avidemux window.
click hold and drag avidemux back to top of screen
Reduce video plane by using [2][1] from numeric keyboard.
Text menu: View: Toolbars: disable some.
I was able to reduce avidemux canvas size to 595 by 359.