Mouse events on Cocoa macOS stopped working.

[mcourteaux]

After running git bisect, I found this to be the offending commit:

ea642fe9ff17e90a0ccc0ec95d007859c4ab02bc is the first bad commit
commit ea642fe9ff17e90a0ccc0ec95d007859c4ab02bc
Author: Sam Lantinga <[email protected]>
Date:   Wed Jan 15 23:34:20 2025 -0800

    cocoa: clear mouse focus based on NSEventTypeMouseExited events (#11991)
    
    We can't directly set the mouse focus since we may get spammed by entered/exited events,
    but we can process the current focus later in the mouseMoved handler in line with the
    mouse motion event sequence.
    
    Fixes https://github.com/libsdl-org/SDL/issues/8188

 src/video/cocoa/SDL_cocoaevents.m |  2 ++
 src/video/cocoa/SDL_cocoamouse.h  |  1 +
 src/video/cocoa/SDL_cocoamouse.m  | 28 ++++++++++++++++++++++------
 src/video/cocoa/SDL_cocoawindow.m |  6 ++++++
 4 files changed, 31 insertions(+), 6 deletions(-)

Mouse events behave very wonky, they 100% don't work the first few seconds/moments/events. Then they start working but very oddly. I haven't fully figured out what's going on. I'm suspecting a state-bug, given the simple changes in the commit. @slouken you seemed to have edited this code last in #11991, while fixing #8188.

[mcourteaux]

I'm not 100% sure what the mechanic is, but I suspect that the initial mouse entered event is missing for me when the window spawns underneath the cursor. Otherwise I don't know immediately under which conditions the Cocoa_MouseFocus global is not set. Leaving and reentering the window with the mouse does not fix the issue, so I'm suspecting my macOS version (12.7) doesn't report those enter / leave events the same way as it happens on a more modern version of macOS?

This quick-and-dirty test fixes the mouse again:

--- a/src/video/cocoa/SDL_cocoamouse.m
+++ b/src/video/cocoa/SDL_cocoamouse.m
@@ -480,6 +480,9 @@ void Cocoa_HandleMouseEvent(SDL_VideoDevice *_this, NSEvent *event)
         return;
     }
 
+    // Any event coming through clearly was happening inside a window.
+    Cocoa_MouseFocus = [event window];
+
     mouse = SDL_GetMouse();
     data = (SDL_MouseData *)mouse->internal;
     if (!data) {

However, perhaps even this is a slightly better fix (also works):

diff --git a/src/video/cocoa/SDL_cocoamouse.m b/src/video/cocoa/SDL_cocoamouse.m
index 77ebf109d..b6fa254b2 100644
--- a/src/video/cocoa/SDL_cocoamouse.m
+++ b/src/video/cocoa/SDL_cocoamouse.m
@@ -447,10 +447,9 @@ void Cocoa_HandleMouseEvent(SDL_VideoDevice *_this, NSEvent *event)
     float deltaX, deltaY;
     bool seenWarp;
 
+    Cocoa_MouseFocus = [event window];
+
     switch ([event type]) {
-    case NSEventTypeMouseEntered:
-        Cocoa_MouseFocus = [event window];
-        return;
     case NSEventTypeMouseExited:
         Cocoa_MouseFocus = NULL;
         return;