Call Yield() to unblock the main thread when refreshing.

Also, we don't seem to need this solar mutex locking and checking for
needs repaint flag here anymore, and not having these make the streaming
much faster esp on Windows.

Change-Id: I6e8ae82e5d986492ac576d28f11e2afffe954bc2

sc/source/ui/docshell/datastream.cxx

@@ -65,15 +65,11 @@ private:
     {
         while (!mbTerminate)
         {
-            // wait for a small amount of time, so that
-            // painting methods have a chance to be called.
-            // And also to make UI more responsive.
-            TimeValue const aTime = {0, 100000};
             maStart.wait();
             maStart.reset();
             if (!mbTerminate)
                 while (mpDataStream->ImportData())
-                    wait(aTime);
+                    ;
         };
     }
 };
@@ -352,6 +348,7 @@ void DataStream::SetRefreshOnEmptyLine( bool bVal )
 void DataStream::Refresh()
 {
     // Hard recalc will repaint the grid area.
+    Application::Yield();
     mpDocShell->DoHardRecalc(true);
     mpDocShell->SetDocumentModified(true);
 
@@ -513,14 +510,10 @@ void DataStream::Text2Doc() {}
 
 bool DataStream::ImportData()
 {
-    SolarMutexGuard aGuard;
     if (!mbValuesInLine)
         // We no longer support this mode. To be deleted later.
         return false;
 
-    if (ScDocShell::GetViewData()->GetViewShell()->NeedsRepaint())
-        return mbRunning;
-
     Text2Doc();
     return mbRunning;
 }