Initial OGComboBox implementation.

Only support for text so far.

headers/OGBox.h

@@ -2,7 +2,6 @@
 
 @interface OGBox: OGWidget
 + box;
-
 - (void)appendChild: (OGWidget*)child
 	     expand: (BOOL)expand
 	       fill: (BOOL)fill

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

headers/OGComboBoxItem.h

@@ -0,0 +1,12 @@
+#import <ObjFW/OFString.h>
+
+@interface OGComboBoxItem: OFObject
+{
+	OFString *label;
+}
+
+@property (copy) OFString *label;
+
++ comboBoxItemWithLabel: (OFString*)label;
+- initWithLabel: (OFString*)label;
+@end