More preparation for the OS X window move/resize code: uiMainStep() is split into an internal function that takes a pre-sendEvent: interception specifically intended for internal loops.

darwin/main.m

@@ -169,10 +169,17 @@ void uiMainSteps(void)
 	stepsIsRunning = YES;
 }
 
+int uiMainStep(int wait)
+{
+	return mainStep(wait, ^(NSEvent *e) {
+		return NO;
+	});
+}
+
 // see also:
 // - http://www.cocoawithlove.com/2009/01/demystifying-nsapplication-by.html
 // - https://github.com/gnustep/gui/blob/master/Source/NSApplication.m
-int uiMainStep(int wait)
+int mainStep(int wait, BOOL (^interceptEvent)(NSEvent *e))
 {
 	NSDate *expire;
 	NSEvent *e;
@@ -196,6 +203,7 @@ int uiMainStep(int wait)
 			return 1;
 
 		type = [e type];
+		if (!interceptEvent(e))
 			[realNSApp() sendEvent:e];
 		[realNSApp() updateWindows];
 

darwin/uipriv_darwin.h

@@ -34,7 +34,7 @@
 extern void finalizeMenus(void);
 extern void uninitMenus(void);
 
-// init.m
+// main.m
 @interface applicationClass : NSApplication
 @end
 // this is needed because NSApp is of type id, confusing clang
@@ -43,6 +43,7 @@ extern void uninitMenus(void);
 @property (strong) menuManager *menuManager;
 @end
 #define appDelegate() ((appDelegate *) [realNSApp() delegate])
+extern int mainStep(int wait, BOOL (^interceptEvent)(NSEvent *));
 
 // util.m
 extern void disableAutocorrect(NSTextView *);