Initial OGComboBox implementation.

Only support for text so far.

headers/OGComboBox.h

@@ -0,0 +1,27 @@
+#import "OGWidget.h"
+#import "OGComboBoxItem.h"
+
+@class OGComboBox;
+
+@protocol OGComboBoxDelegate <OFObject>
+@optional
+- (void)comboBoxWasChanged: (OGComboBox*)comboBox;
+@end
+
+@protocol OGComboBoxDataSource <OFObject>
+- (size_t)numberOfItemsInComboBox: (OGComboBox*)comboBox;
+- (OGComboBoxItem*)comboBox: (OGComboBox*)comboBox
+		itemAtIndex: (size_t)index;
+@end
+
+@interface OGComboBox: OGWidget
+{
+	id <OGComboBoxDelegate> delegate;
+	id <OGComboBoxDataSource> dataSource;
+}
+
+@property (assign) id <OGComboBoxDelegate> delegate;
+@property (assign) id <OGComboBoxDataSource> dataSource;
+
++ comboBox;
+@end