This commit fixes 3 crashes when reverting a document:

1) crash in GuiWorkArea::paintEvent(), this one is solved by by encapsulating the file loading in LyXView by busy(true)/busy(false) and by disabling/enabling the work area update in GuiView::busy().

2) crash in the cursor blinking because the cursor is timed out at the moment you click on "Revert". So the blinking cursor is now disabled/enabled in GuiView::busy().

3) crash in BufferView::setBuffer() because the current buffer was already closed folling the "revert" command. 
* BufferView::loadLyXFile(): set buffer_ to 0 in case of a reload (when document is reverted)

* LyXView:
  - busy() is not const anymore (work_area_ is modified in GuiView) 
  - loadLyXFile(): encapsulate the file loading with busy(true)/busy(false)
  - setBuffer(): encapsulate the buffer-switching with busy(true)/busy(false)

* GuiView::busy()
  - disable/enable workarea updates.
  - disable/enable blinking cursor.

* WorkArea: new startBlinkingCursor() and stopBlinkingCursor() methods.

* rowpainter.C:
  - paintText(): make sure there is a Buffer from which to paint.


git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15556 a592a061-630c-0410-9148-cb99ea01b6c8

src/BufferView.C

@@ -246,6 +246,7 @@ bool BufferView::loadLyXFile(string const & filename, bool tolastfiles)
 		if (!theBufferList().close(theBufferList().getBuffer(s), false))
 			return false;
 		// Fall through to new load. (Asger)
+		buffer_ = 0;
 	}
 
 	Buffer * b = 0;

src/frontends/LyXView.C

@@ -105,6 +105,8 @@ Buffer * LyXView::buffer() const
 
 void LyXView::setBuffer(Buffer * b)
 {
+	busy(true);
+
 	if (work_area_->bufferView().buffer())
 		disconnectBuffer();
 
@@ -129,12 +131,15 @@ void LyXView::setBuffer(Buffer * b)
 	updateLayoutChoice();
 	updateWindowTitle();
 	updateStatusBar();
+	busy(false);
 	work_area_->redraw();
 }
 
 
 bool LyXView::loadLyXFile(string const & filename, bool tolastfiles)
 {
+	busy(true);
+
 	if (work_area_->bufferView().buffer())
 		disconnectBuffer();
 
@@ -149,6 +154,7 @@ bool LyXView::loadLyXFile(string const & filename, bool tolastfiles)
 		showErrorList("Parse");
 	}
 	updateStatusBar();
+	busy(false);
 	work_area_->redraw();
 	return loaded;
 }

src/frontends/LyXView.h

@@ -93,7 +93,7 @@ public:
 	virtual void saveGeometry() = 0;
 
 	/// show busy cursor
-	virtual void busy(bool) const = 0;
+	virtual void busy(bool) = 0;
 
 	virtual Toolbars::ToolbarPtr makeToolbar(ToolbarBackend::Toolbar const & tbb) = 0;
 

src/frontends/WorkArea.C

@@ -119,6 +119,18 @@ BufferView const & WorkArea::bufferView() const
 }
 
 
+void WorkArea::stopBlinkingCursor()
+{
+	cursor_timeout_.stop();
+}
+
+
+void WorkArea::startBlinkingCursor()
+{
+	cursor_timeout_.restart();
+}
+
+
 void WorkArea::checkAndGreyOut()
 {
 	if (greyed_out_)

src/frontends/WorkArea.h

@@ -85,6 +85,9 @@ public:
 	virtual void redraw();
 	///
 	void checkAndGreyOut();
+	///
+	void stopBlinkingCursor();
+	void startBlinkingCursor();
 
 protected:
 	/// grey out (no buffer)

src/frontends/qt4/GuiView.C

@@ -12,9 +12,10 @@
 
 #include <config.h>
 
-#include "GuiImplementation.h"
-
 #include "GuiView.h"
+
+#include "GuiImplementation.h"
+#include "GuiWorkArea.h"
 #include "QLMenubar.h"
 #include "QLToolbar.h"
 #include "QCommandBuffer.h"
@@ -288,13 +289,19 @@ void GuiView::show()
 }
 
 
-void GuiView::busy(bool yes) const
+void GuiView::busy(bool yes)
 {
-	if (yes)
+	static_cast<GuiWorkArea *>(work_area_)->setUpdatesEnabled(!yes);
+
+	if (yes) {
+		work_area_->stopBlinkingCursor();
 		QApplication::setOverrideCursor(Qt::WaitCursor);
-	else
+	}
+	else {
+		work_area_->startBlinkingCursor();
 		QApplication::restoreOverrideCursor();
 	}
+}
 
 
 Toolbars::ToolbarPtr GuiView::makeToolbar(ToolbarBackend::Toolbar const & tbb)

src/frontends/qt4/GuiView.h

@@ -63,7 +63,7 @@ public:
 		int posx, int posy,
 		bool maximize);
 	virtual void saveGeometry();
-	virtual void busy(bool) const;
+	virtual void busy(bool);
 	Toolbars::ToolbarPtr makeToolbar(ToolbarBackend::Toolbar const & tbb);
 	virtual void updateStatusBar();
 	virtual void message(lyx::docstring const & str);

src/rowpainter.C

@@ -898,6 +898,9 @@ void paintPar
 void paintText(BufferView & bv, ViewMetricsInfo const & vi,
 	       Painter & pain)
 {
+	if (!bv.buffer())
+		return;
+
 	LyXText & text = bv.buffer()->text();
 	bool const select = bv.cursor().selection();