I found two ways to reproduce this bug on macOS 26.5 with Firefox 150. Both methods reproduce this 100% of the time. 1) 500ms Timer Race - Open a first window on the screen, taking up most of the screen. - Open a second window using cmd-n, it will be the same size at the first (slightly offset as expected) - Put your fingers on the cmd-n buttons so you can do it really fast. - Resize the second window to be roughly half the width of the first - Within less than half a second (500ms) of completing the resize, hit cmd-n - The new window will incorrectly be the size of the first window, not the second one This is because there is a 500ms timer that runs before size changes are persisted, so the new size of the second window is not persisted yet when you created the third window. I'm not really sure this case is worth fixing. 2) Minimizing Bug - Open a first window on the screen, taking up most of the screen. - Open a second window using cmd-n, it will be the same size at the first (slightly offset as expected) - Resize the second window to be roughly half the width of the first - Minimize the second window using cmd-m - Wait a few seconds, then deminimize the second window by clicking on its dock icon - Hit cmd-n to open a third window - The new window will incorrectly be the size of the first window, not the second one This happens because when you minimize the second window, the first window becomes the main window and its size is persisted. When you deminimize the second window and it becomes the main window again, its size should be persisted but it isn't. For some reason the new main window persists its size when you minimize a windows, but when you deminimize a window its size is not persisted. This behavioral asymmetry causes the bug. I think this should be fixed.
Bug 429952 Comment 16 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
I found two ways to reproduce this bug on macOS 26.5 with Firefox 150. Both methods reproduce this 100% of the time. 1) 500ms Timer Race - Open a first window on the screen, taking up most of the screen. - Open a second window using cmd-n, it will be the same size at the first (slightly offset as expected) - Put your fingers on the cmd-n buttons so you can do it really fast, but don't actually do it yet - Resize the second window to be roughly half the width of the first - Within less than half a second (500ms) of completing the resize, hit cmd-n - The new window will incorrectly be the size of the first window, not the second one This is because there is a 500ms timer that runs before size changes are persisted, so the new size of the second window is not persisted yet when you created the third window. I'm not really sure this case is worth fixing. 2) Minimizing Bug - Open a first window on the screen, taking up most of the screen. - Open a second window using cmd-n, it will be the same size at the first (slightly offset as expected) - Resize the second window to be roughly half the width of the first - Minimize the second window using cmd-m - Wait a few seconds, then deminimize the second window by clicking on its dock icon - Hit cmd-n to open a third window - The new window will incorrectly be the size of the first window, not the second one This happens because when you minimize the second window, the first window becomes the main window and its size is persisted. When you deminimize the second window and it becomes the main window again, its size should be persisted but it isn't. For some reason the new main window persists its size when you minimize a windows, but when you deminimize a window its size is not persisted. This behavioral asymmetry causes the bug. I think this should be fixed.