Work around file tracking issue when building example files.
Adjust initial sizes of main window and instrument window.
Align About window contents to horizontal center.
Show instrument name in instrument window title.
Adjust event list window size.
Make sure that cancelling the open dialog does not create a new tracker instance.
Merge pull request #280 from kagu/window_appearance

Window appearance
Merge pull request #282 from kagu/fix_open_cancel

Make sure that cancelling the open dialog does not create a new tracker instance
Merge pull request #278 from kagu/fix_build_examples

Work around file tracking issue when building example files