Added handling of dragged files.
 Added "Settings" and "About" items in the system menu.
 Added hotkeys.
 Added hints for buttons.
 Added confirmation to replace an existing button.
 Added hiding the window when left clicking on the tray icon.
 Added option "Hide on call".
 Added prevention of launching multiple copies of the application.
 Added option to resize icons.
 Added caching icons for a faster launch of the program.
 Various minor improvements.
 Fixed various bugs.