Hi TempodiBasic. For each point:
1. not yet;
1.1 not yet;
1.2 yes; InForm's editor uses that trick. When you click File->Open or Edit->Z-ordering, the new "dialog" is achieved by showing a frame that covers all the screen. That frame is hidden at -600, -600 during program execution and is only shown when requested. You can inspect UiEditor.bas to see how I did it. Look for "OpenFrame" and "ZOrdering" in the code.
2. I haven't tried pushing it to a limit yet. There are no constraints in code and you can probably have as many items as your system's memory allows. If you do hit a limit, please let me know.
3. Yes.
3.1 No. You should never call _DISPLAY as InForm is already doing that at a regular interval. If some change doesn't show immediately, you must request a full redraw by setting
__UI_ForceRedraw = True (global redraw) or by setting
Control(ControlID).Redraw = True (per control) when needed.
4. Not yet, but that's planned (issue #20 at
https://github.com/FellippeHeitor/InForm/milestone/3)
4.1 not yet (see above).