Pictures will show wrong resize behavior at the beginning of a slide show, when the window size exceeds the display size. As the Window will be shown in full screen anyway, an initial window size of 1x1px should support all display sizes.
If the window defined in src/mainwindow.ui exceeds the size of the
display, the program behaves weirdly. Growing the window size even further
leads to crashes. Reducing the window size to 1x1px seems to work fine
and should be smaller than any display size.
In case the screen resulution did not match the size set in
mainwindow.ui, you may only see part of the image shown. Putting the
window in full screen explicitly fixes that issue.
Addes .jpeg and .JPEG in the file whitelist to suppot .jpeg files as well.
.jpg is just a shortcut for .jpeg files because old OSes did only support 3-character fileformats.
