Correct update of TextView text run on font change.

* Fixes #4698 - font preference changes were not applied
  on the next message;
* The source of problem is resetting of the text run array after
  applying new font with SetFontAndColor function. Proposed solution
  updates the text run array items fonts directly without resetting
  it them and without loosing any styling and color quiting
  information;
* This is result of completing GCI 2011 task.

Signed-off-by: Siarzhuk Zharski <[email protected]>

src/apps/mail/Content.cpp

@@ -680,7 +680,7 @@ TContentView::MessageReceived(BMessage *msg)
 		{
 			BFont *font;
 			msg->FindPointer("font", (void **)&font);
-			fTextView->SetFontAndColor(0, LONG_MAX, font);
+			fTextView->UpdateFont(font);
 			fTextView->Invalidate(Bounds());
 			break;
 		}
@@ -919,6 +919,21 @@ TTextView::~TTextView()
 }
 
 
+void
+TTextView::UpdateFont(const BFont* newFont)
+{
+	fFont = *newFont;
+
+	// update the text run array safely with new font
+	text_run_array *runArray = RunArray(0, LONG_MAX);
+	for (int i = 0; i < runArray->count; i++)
+		runArray->runs[i].font = *newFont;
+
+	SetRunArray(0, LONG_MAX, runArray);
+	FreeRunArray(runArray);
+}
+
+
 void
 TTextView::AttachedToWindow()
 {

src/apps/mail/Content.h

@@ -177,6 +177,7 @@ class TTextView : public BTextView {
 
 		void AddQuote(int32 start, int32 finish);
 		void RemoveQuote(int32 start, int32 finish);
+		void UpdateFont(const BFont* newFont);
 
 		void	WindowActivated(bool flag);
 		void	Undo(BClipboard *clipboard);