[Bug 30614] New: Builtin richedit extremely slow at appending text when window is hidden

http://bugs.winehq.org/show_bug.cgi?id=30614

Bug #: 30614
           Summary: Builtin richedit extremely slow at appending text when
                    window is hidden
           Product: Wine
           Version: 1.5.2
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: richedit
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]
    Classification: Unclassified

While looking into bug 30593, I discovered that hidden richedit controls
were way slower than visible ones at appending text.  Running the attached
test program with
   perf record wine hidden_richedit.exe
   perf report
showed some time in ME_InvalidateMarkedParagraphs.  +relay showed that 
function calling InvalidateRect many, many times.  Adding a trace showed
that most of the calls were redundant, and covered increasingly offscreen
regions.
Native riched20 works around the problem.

The attached kludge patch skips the offscreen InvalidateRects, and
makes the test program run in a reasonable amount of time with builtin
riched20.
(Not quite as fast as native riched20, but tolerable.)