- Stop passing hwnd around when we're passing EDITSTATE.

- Merge the non-obsolete bits of EDIT.TODO into edit.c.
- Some cleanups, and simplifications.

controls/EDIT.TODO

@@ -1,205 +0,0 @@
-/*
- *	Outdated !!!
- *
- *	The edit control is under reconstruction
- *	New documentation will be provided when I'm done
- *
- *	Please contact me before you send in bug fixes, as the code
- *	might have changed already.  However, keep reporting those
- *	bugs ... I might not know about them, yet.
- *
- *	Frans van Dorsselaer
- *	dorssel@MolPhys.LeidenUniv.nl
- */
-This file gives some information about the code in edit.c.  If you want to
-change, add, or fix code, please read this text.  If you're not interested
-in doing actual work on edit.c only C & D will be of interest to you.
-
-A) basic policy
-B) special functions
-C) not implemented / implementation ideas / implementation problems
-D) known bugs / features
-
-A) Basic Policy
-
-All messages are handled by EditWndProc(), which is the only external
-function call.  All other functions are static (local to edit.c).
-
-All Windows Messages (WM_XXX) are 32-bit, since the edit control is now a
-32-bit registered class.  The message are dealt with through the helper
-functions EDIT_WM_XXX().
-
-The edit control messages can be either 16 or 32 bit, depending on the type
-of application that sends the message.  Wherever possible EditWndProc()
-converts the 16-bit message parameters to parameters corresponding to their
-32-bit counterparts.  The message is then handled by the appropriate
-EDIT_EM_XXX() helper function. Sometimes it is not possible to handle the
-16-bit and 32-bit versions in the same way, in which case both helper
-functions EDIT_EM_XXX16() and EDIT_EM_XXX() are defined.
-
-All other functions are called EDIT_XXX().
-
-Note: Sometimes a function is internally used a bit different than the specs
-of a similar function.  For instance EDIT_SetSel() is used internally and
-should not be mixed up with EDIT_EM_SetSel(), a message handler that _does_
-conform to the specs of EM_SETSEL.
-
-The code has been made in such a way, that functions try to call other
-(documented) functions if that is sufficient.  This might sometimes not be
-the most efficient way, but it keeps the code clear.  This way I tried to
-keep the number of functions that rely on the internal EDITSTATE structure
-as low as possible.  For instance EDIT_WM_Cut() simply calls EDIT_WM_Copy()
-and EDIT_WM_Clear().  The latter two are well documented message handlers,
-so as long as they are right EDIT_WM_Cut() will never have to change again.
-
-Example:
-The best thing to do, when you want to know the offset of line 3, is calling
-EDIT_EM_LineIndex().  Again this is a well documented message handler. 
-Don't look at es->LineDefs[2].offset.  It would just be another reference to
-the internal structure, and that would make it more difficult to change
-things. Refer to EDIT_WM_???? and EDIT_EM_????? functions as much as
-possible.
-
-The WND * pointer is used internally whenever possible.  Although it is not
-the real HWND, it improves performance enough to use it.
-
-All displaying is done by invalidating regions / rects.  Only
-EDIT_EM_LineScroll() uses direct painting.  This way things become much
-faster.  Although sometimes the response time might appear to be slow, it
-would be much slower even, when everything would be painted instantly.  This
-is especially true for scrollbar tracking and selection changes..
-
-The text buffer is a kind of tricky.  Initially the edit control allocates a
-HLOCAL32 buffer (32 bit linear memory handler).  However, 16 bit application
-might send a EM_GETHANDLE message and expect a HLOCAL16 (16 bit SEG:OFF
-handler).  From that moment on we have to keep using this 16 bit memory
-handler, because it is supposed to be valid at all times after EM_GETHANDLE. 
-What we do is create a HLOCAL16 buffer, copy the text, and do pointer
-conversion.
-
-
-
-B) Special functions
-
-Several helper functions try to make your life easier when dealing with the
-allocated buffer.  In principle Windows can move memory blocks around unless
-they are locked.  Currently, WINE doesn't do this, but it might in the
-future.
-
-For this reason there is a nice EDIT_GetPointer() function, which locks the
-heap buffer *only once*, no matter how often it is called. It then returns a
-nice 32-bit pointer to linear memory. Calling EDIT_GetPointer() is very fast
-if the buffer is already locked, so you can call it whenever you feel it
-*might* be useful.
-
-At the end of EditWndProc(), EDIT_ReleasePointer() is automatically called
-which cleans up the initialized pointer.  So you don't have to worry about
-unlocking the memory block. This way, the buffer gets locked / unlocked only
-once every message, although EDIT_GetPointer() may actually have been called
-a hundred times.  Only when the actual HLOCAL is needed (for example to
-ReAlloc), an extra call (besides the cleanup at the end of EditWndProc()) to
-EDIT_ReleasePointer() is needed.  Look for instance in EDIT_MakeFit().
-
-This brings us to EDIT_MakeFit().  It automatically re-allocates the buffer
-if the size parameter > buffersize.  If everything is successful TRUE is
-returned, otherwise FALSE.  Only when the buffer contents may grow you need
-to call EDIT_MakeFit().  Currently this is only in EDIT_ReplaceSel() and
-EDIT_WM_SetText().
-
-EDIT_GetPointer(), EDIT_ReleasePointer and EDIT_MakeFit() are aware of the
-HLOCAL32 / HLOCAL16 business.
-
-EDIT_BuildLineDefs() is the most important function in edit.c.  It builds
-the internal EDITSTATE structure.  As soon as text *might* have changed, or
-when the appearance of the text on the screen *might* have changed, call
-this function !  This includes changes of screen size, change of the font,
-clipboard actions, etc. etc.  Most other functions that rely on EDITSTATE,
-rely on the stuff this function builds.
-
-
-
-C) Not Implemented / Implementation Ideas / Implementation Problems
-
-Styles:
-
-- ES_CENTER
-- ES_RIGHT
-- ES_NUMBER (new since win95)
-- ES_OEMCONVERT
-- ES_WANTRETURN
-
-None of these should be difficult to include.  I just didn't have the time
-yet.  Feel free ...
-
-- ES_AUTOVSCROLL (every multi line control *is* auto vscroll)
-- ES_AUTOHSCROLL (every single line control *is* auto hscroll)
-		 (for multi line controls it works : wordwrap)
-
-Much, much more difficult.  It comes down to this: When there is no
-autoscrolling, the edit control should first check whether the new text
-(after a typed key for instance) would fit.  If not, an EN_MAXTEXT should be
-sent.  However, currently this would require the actual change to be made,
-then call EDIT_BuildLineDefs() and then find out that the new text doesn't
-fit.  After all this, things should be put back in the state before the
-changes.  Given the fact that even normal UNDO doesn't work ...
-
-Messages:
-
-- EM_SETRECT
-- EM_SETRECTNP
-- EM_SETMARGINS (new since win95)
-- EM_FMTLINES
-
-These shouldn't be really difficult either.  They just confine the visual
-output to something different than the client rectangle.  Currently the
-client area is used everywhere in the code.  At some points this should
-really be so (GetClientRect32()), whereas at other points it should be the
-format rectangle (EDIT_EM_GetRect()). Both functions are now used, but
-inconsistently and mixed up ! If you implement the formatting rectangle /
-margins, be sure to check all references to RECT's, and how they are /
-should be obtained.
-
-- EM_FMTLINES
-
-This means: insert or remove the soft linebreak character (\r\r\n). Probably
-invented by MS to suit their implementation of the edit control.  However,
-with WINE's implementation I've never come up with occasions where it is
-actually useful (we never insert \r\r\n, and applications always request
-removal).  If you are a purist ... implementation shouldn't be difficult. 
-Take care to check if the text still fits the buffer after insertion. If
-not, notify with EN_ERRSPACE.
-
-- WM_UNDO (=EM_UNDO)
-
-I'm working on it.  It is, however, not trivial.  Luckily the only function
-where actual text changes is EM_REPLACESEL, so this is the only spot where
-we have to worry about UNDO capabilities. Before you try: contact me.  I
-already have ideas and might start implementing it myself really soon.
-
-- EM_SETWORDBREAKPROC
-
-Not really difficult.  It used to work, but since we moved to 32 bits there
-are now two kinds of callback functions.  And I don't know the 32-bit specs
-for the WordBreakProc() ...  Look it up and uncomment the code that is still
-there for 16 bit callback.
-
-- EM_SCROLL
-
-Supposed to be the same as WM_VSCROLL, but not quite.  In other words:
-poorly documented.  Somebody that knows ?
-
-
-
-D) Known bugs / Features
-
--	Scrollbar tracking is broken.
--	Turning on WordWrap with 16-bit Notepad leaves part of the horizontal
-	scrollbar visible (problem with WM_ERASEBKGND ???).
--	FIXME's (grep for them).
-
-
-I am working on Undo capabilities.  If you want to do things, other than bug
-fixes, please mail me so we can synchronize.
-
-Frans van Dorsselaer
-dorssel@rulhm1.LeidenUniv.nl