One thing that exists in the dialog but does not exist as a regular input on MMF is tabs. I like to use tabs to organize input screens. Right now on a app I'm developing I'm just doing most of the input in a dialog.
In regards to dialogs it would be nice to have a bit more control over formatting.
1.) Be able to add images to a dialog.
2.) Format text. When doing a label (i.e. Static Text) there's no formatting options. Font type, style, size, color.
3.) X/Y coordinates. In MMF I can align other editboxes and other objects up perfectly by modifying the X/Y value in the objects properties. It would be nice to be able to do similar to objects (or controls? if that's what they're called) in dialog boxes.