Implemented uiCheckbox on Mac OS X. Before I implement it on GTK+ I'll go back and add uiCheckboxChecked() and uICheckboxSetChecked().

new/checkbox_darwin.m

@@ -0,0 +1,78 @@
+// 7 april 2015
+#import "uipriv_darwin.h"
+
+@interface uiCheckboxNSButton : NSButton
+@property uiControl *uiC;
+@property void (*uiOnToggled)(uiControl *, void *);
+@property void *uiOnToggledData;
+@end
+
+@implementation uiCheckboxNSButton
+
+- (void)viewDidMoveToSuperview
+{
+	if (uiDarwinControlFreeWhenAppropriate(self.uiC, [self superview])) {
+		[self setTarget:nil];
+		self.uiC = NULL;
+	}
+	[super viewDidMoveToSuperview];
+}
+
+- (IBAction)uiCheckboxToggled:(id)sender
+{
+	(*(self.uiOnToggled))(self.uiC, self.uiOnToggledData);
+}
+
+@end
+
+static void defaultOnToggled(uiControl *c, void *data)
+{
+	// do nothing
+}
+
+uiControl *uiNewCheckbox(const char *text)
+{
+	uiControl *c;
+	uiCheckboxNSButton *cc;
+
+	c = uiDarwinNewControl([uiCheckboxNSButton class], NO, NO);
+	cc = (uiCheckboxNSButton *) uiControlHandle(c);
+	cc.uiC = c;
+
+	[cc setTitle:toNSString(text)];
+	[cc setButtonType:NSSwitchButton];
+	[cc setBordered:NO];
+	setStandardControlFont((NSControl *) cc);
+
+	[cc setTarget:cc];
+	[cc setAction:@selector(uiCheckboxToggled:)];
+
+	cc.uiOnToggled = defaultOnToggled;
+
+	return cc.uiC;
+}
+
+char *uiCheckboxText(uiControl *c)
+{
+	uiCheckboxNSButton *cc;
+
+	cc = (uiCheckboxNSButton *) uiControlHandle(c);
+	return strdup(fromNSString([cc title]));
+}
+
+void uiCheckboxSetText(uiControl *c, const char *text)
+{
+	uiCheckboxNSButton *cc;
+
+	cc = (uiCheckboxNSButton *) uiControlHandle(c);
+	[cc setTitle:toNSString(text)];
+}
+
+void uiCheckboxOnToggled(uiControl *c, void (*f)(uiControl *, void *), void *data)
+{
+	uiCheckboxNSButton *cc;
+
+	cc = (uiCheckboxNSButton *) uiControlHandle(c);
+	cc.uiOnToggled = f;
+	cc.uiOnToggledData = data;
+}