Depreciated controls in Xojo 2021r3

[antijingoist]

Xojo deprecated many controls in 2021, replacing them with new ones.

Using imSplitter in a new project still works, as long as the code is updated to use the new Desktop objects:

• DesktopContainer instead of ContainerControl
• DesktopControl instead of Control
• DesktopUIControl instead of RectControl

Older projects continue to use the older objects, so making the changes to the sample project would likely break it (reason a pull request isn't included).

[tempelmann]

Something you can fix, however: It's "deprecated", without "i". It's a common mistake.