[1] Creating GUI applications on Amiga was difficult for a very long time, mainly because the programmer got only a minuscule amount of support from the operating system.

Beginning with Kickstart 2.0, the gadtools.library was a step in the right direction, however, even using this library to generate complex and flexible interfaces remained difficult and still required a great deal of patience.

Starting from MUI 3.9 an unrestricted version is integrated with MorphOS, but a shareware key is still required to activate all user configuration options in AmigaOS.

In MUI application the programmer only defines logical structure of the GUI and the layout is determined at run time depending on user configuration.

It can also automatically switch into smaller font or hide UI elements if there is not enough space on screen to display window with full contents.

The MagicWB companion to MUI made use of this extended palette to provide more attractive icons to replace the dated Workbench defaults.