macos - Change mouse cursor over inactive NSWindow

Question

I have subclassed NSWindow and I have a MYWindow class implementing the following method:

-(void)resetCursorRects {
    NSImage *image = [NSImage imageNamed:@"cursor.png"];
    [image setSize:NSMakeSize(32, 32)];
    NSCursor *cursor = [[NSCursor alloc] initWithImage:image hotSpot:NSMakePoint(1, 1)];
    [super resetCursorRects];    
    [self addCursorRect:[self bounds] cursor:cursor];
}

This will change the cursor for the whole window and I will see cursor.png instead of the default mouse pointer. The problem is that this only works if the MYWindow is set to the key window which is of course non trivial to make it.

In the beginning of my project I just have one main window but now I need to have two different MYWindow. The problem with two windows it is not possible to set both as the key window and hence the custom mouse pointer is only displayed on the active window. I need to click the other window to make the cursor appear.

Is there any way around this? So I get a custom cursor on both windows?

Edit: Tried NSTrackingArea

I added this to my content view's init method:

self.trackingArea = [[NSTrackingArea alloc] initWithRect:[self frame] options: (NSTrackingCursorUpdate | NSTrackingActiveAlways | NSTrackingMouseMoved) owner:self userInfo:nil];
[self addTrackingArea:self.trackingArea];

Then I overrided cursorUpdate: like this:

-(void)cursorUpdate:(NSEvent *)event {
    NSLog(@"event : %@", event);
    [[NSCursor crosshairCursor] set];
}

This makes the crosshairCursor show when the NSWindow that contains the NSImageView derived class is key window. But if I make another NSWindow within the app the key window, the cursor returns to the standard cursor again. Am I doing something wrong?

Answer 1

I struggled with this problem for a long period of time and I think there is only one way to change mouse cursor over inactive application (over non-foreground window). This is hacky and magic way.

Before calling pretty standard:

[[NSCursor pointingHandCursor] push];

You have to call:

void CGSSetConnectionProperty(int, int, int, int);
int CGSCreateCString(char *);
int CGSCreateBoolean(BOOL);
int _CGSDefaultConnection();
void CGSReleaseObj(int);
int propertyString, boolVal;

propertyString = CGSCreateCString("SetsCursorInBackground");
boolVal = CGSCreateBoolean(TRUE);
CGSSetConnectionProperty(_CGSDefaultConnection(), _CGSDefaultConnection(), propertyString, boolVal);
CGSReleaseObj(propertyString);
CGSReleaseObj(boolVal);

Or if you are using Swift:

Put this in your YourApp-Bridging-Header.h:

typedef int CGSConnectionID;
CGError CGSSetConnectionProperty(CGSConnectionID cid, CGSConnectionID targetCID, CFStringRef key, CFTypeRef value);
int _CGSDefaultConnection();

And then call:

let propertyString = CFStringCreateWithCString(kCFAllocatorDefault, "SetsCursorInBackground", 0)
CGSSetConnectionProperty(_CGSDefaultConnection(), _CGSDefaultConnection(), propertyString, kCFBooleanTrue)