Add method setUsesSingleLineMode: and usesSingleLineMode

Headers/AppKit/NSCell.h

@@ -202,6 +202,8 @@ enum {
     unsigned subclass_bool_four: 1;
     // Set while the cell is edited/selected
     unsigned in_editing: 1;
+    // Set if cell uses single line mode.
+    unsigned _uses_single_line_mode:1;
   } _cell;
   NSUInteger _mouse_down_flags;
   NSUInteger _action_mask;
@@ -330,6 +332,10 @@ enum {
 - (NSLineBreakMode)lineBreakMode;
 - (void)setLineBreakMode:(NSLineBreakMode)mode;
 #endif
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_6, GS_API_LATEST)
+- (void) setUsesSingleLineMode: (BOOL)flag;
+- (BOOL) usesSingleLineMode;
+#endif
 
 //
 // Target and Action 

Source/NSCell.m

@@ -2869,6 +2869,17 @@ static NSColor *dtxtCol;
   // FIXME: implement this
   return;
 }
+
+- (void) setUsesSingleLineMode: (BOOL)flag
+{
+  _cell._uses_single_line_mode = flag;
+}
+
+- (BOOL) usesSingleLineMode
+{
+  return _cell._uses_single_line_mode;
+}
+
 @end
 
 @implementation NSCell (PrivateMethods)