TRichView.com

This demo enumerates all available fonts having ARABIC_CHARSET or HEBREW_CHARSET.
Make sure Control Panel -> Regional and Language Options ... option "Install files for complex scripts and right-to-left languages" is checked.

To turn on support of bidirectional text, set RichViewEdit.BiDiMode = rvbdLeftToRight or rvbdRightToLeft.

There is no direct example for these operations.
But some ideas can be found here: http://www.trichview.com/forums/viewtopic.php?t=1421 (table sorting)

Can you give me step-by-step instructions how to reproduce this problem?

The error may occur, for example, because of mismatched calls of SetUndoGroupMode. Do you call this method?

I am not sure how DevExpress buttons work, but probably some button's property must be set to allow it be checked (stay pressed)

No, you can only insert pictures (TBitmap, TMetafile or other, inherited from TGraphic) or Delphi controls in text.

May be I still do not understand the source of the problem. To my opinion, document in zoom = 100% and zoom = 101% must look almost identically. If it is displayed wrong, the whole drawing procedure must be changed, not only displaying in 100%. (Moreover, as far as I know how ScaleRichView works, do...

But I believe in components displaying scaled text, it is always scaled. They do not have two drawing functions, one for scaled text and one for 100% zoom.

EM_POSFROMCHAR is not supported.
As for displaying menu at the caret position, see the demo
Demos\Delphi\Assorted\AutoComplete\

Set rv.RTFReadProperties.UnicodeMode = rvruOnlyUnicode.
rv.RTFReadProperties.TextStyleMode should be rvrsAddIfNeeded for best results.

Update 2007-Nov-5: ScaleRichView v1.3.3

New redrawing method. More accurate scaling. Much faster!

New compiled demo and trial are uploaded.
While this issue was not targeted specially, the new update has a new redrawing method, so please retest it.

Sorry, I do not understand.
Do you mean when you click TEdit in TRichViewEdit's cell, not TEdit but TRichViewEdit acquires focus?

Answered in private message