Fix bug #10902 with cursor positioning at EOB.

 src/xdisp.c (try_window_reusing_current_matrix): Don't move cursor
 position past the first glyph_row that ends at ZV.

src/ChangeLog

+2012-03-02  Eli Zaretskii  <eliz@gnu.org>
+
+	* xdisp.c (try_window_reusing_current_matrix): Don't move cursor
+	position past the first glyph_row that ends at ZV.  (Bug#10902)
+
 2012-03-02  Glenn Morris  <rgm@gnu.org>
 
 	* buffer.c (buffer-list-update-hook): Doc fix.

src/xdisp.c

@@ -16322,7 +16322,10 @@ try_window_reusing_current_matrix (struct window *w)
 	   ++first_row_to_display)
 	{
 	  if (PT >= MATRIX_ROW_START_CHARPOS (first_row_to_display)
-	      && PT < MATRIX_ROW_END_CHARPOS (first_row_to_display))
+	      && (PT < MATRIX_ROW_END_CHARPOS (first_row_to_display)
+		  || (PT == MATRIX_ROW_END_CHARPOS (first_row_to_display)
+		      && first_row_to_display->ends_at_zv_p
+		      && pt_row == NULL)))
 	    pt_row = first_row_to_display;
 	}
 
@@ -16414,7 +16417,9 @@ try_window_reusing_current_matrix (struct window *w)
       if (pt_row)
 	{
 	  for (row = MATRIX_ROW (w->current_matrix, w->cursor.vpos);
-	       row < bottom_row && PT >= MATRIX_ROW_END_CHARPOS (row);
+	       row < bottom_row
+		 && PT >= MATRIX_ROW_END_CHARPOS (row)
+		 && !row->ends_at_zv_p;
 	       row++)
 	    {
 	      w->cursor.vpos++;