Values passed in DRAWTEXTPARAMS are already in average character width
units.

comctl32: toolbar: Move common TB_ADDBUTTONS and TB_INSERTBUTTONS code into a helper function, makes TB_INSERTBUTTON with a text perform a recalc (with testcase).

There was a bug in ME_FindText which would cause the final caracter
offset to be incorrect when a paragraph was crossed while matching
characters.  The problem was the character offset of the wrong
paragraph was used in the calculation of the start offset of the
match.

The text mode is already stored, and EM_SETTEXTMODE already exists.

There was however a bug in EM_MakeEditor that could cause TM_PLAINTEXT
and TM_RICHEDIT to be set at the same time.  This was corrected to ensure
EM_GETTEXTMODE returned the proper mode being used.