In the absence of a more specific lead, the first place in the code I would look for this type of issue is `BrowserParent::SendrealMouseEvent`, specifically the place where we set child-process coordinates into `mRefPoint` [here](https://searchfox.org/mozilla-central/rev/10f46c9c638e0e5935ed9fa12aadc9d0d4e71ade/dom/ipc/BrowserParent.cpp#1468). If the child-process coordinates which are set there look reasonable, the issue is probably with the parent-to-child transform matrix (usually with the code in APZ which computes it). If the child-process coordinates look right, the issue is somewhere during the event dispatch in the content process.
Bug 1888904 Comment 10 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
In the absence of a more specific lead, the first place in the code I would look for this type of issue is `BrowserParent::SendRealMouseEvent`, specifically the place where we set child-process coordinates into `mRefPoint` [here](https://searchfox.org/mozilla-central/rev/10f46c9c638e0e5935ed9fa12aadc9d0d4e71ade/dom/ipc/BrowserParent.cpp#1468). If the child-process coordinates which are set there look reasonable, the issue is probably with the parent-to-child transform matrix (usually with the code in APZ which computes it). If the child-process coordinates look right, the issue is somewhere during the event dispatch in the content process.
In the absence of a more specific lead, the first place in the code I would look for this type of issue is `BrowserParent::SendRealMouseEvent`, specifically the place where we put child-process coordinates into `mRefPoint` [here](https://searchfox.org/mozilla-central/rev/10f46c9c638e0e5935ed9fa12aadc9d0d4e71ade/dom/ipc/BrowserParent.cpp#1468). If the child-process coordinates which are set there look reasonable, the issue is probably with the parent-to-child transform matrix (usually with the code in APZ which computes it). If the child-process coordinates look right, the issue is somewhere during the event dispatch in the content process.
In the absence of a more specific lead, the first place in the code I would look for this type of issue is `BrowserParent::SendRealMouseEvent`, specifically the place where we put child-process coordinates into `mRefPoint` [here](https://searchfox.org/mozilla-central/rev/10f46c9c638e0e5935ed9fa12aadc9d0d4e71ade/dom/ipc/BrowserParent.cpp#1468). If the child-process coordinates which are set there look wrong, the issue is probably with the parent-to-child transform matrix (usually with the code in APZ which computes it). If the child-process coordinates look right, the issue is somewhere during the event dispatch in the content process.
In the absence of a more specific lead, the first place in the code I would look for this type of issue is `BrowserParent::SendRealMouseEvent`, specifically the place where we put child-process coordinates into `mRefPoint` [here](https://searchfox.org/mozilla-central/rev/10f46c9c638e0e5935ed9fa12aadc9d0d4e71ade/dom/ipc/BrowserParent.cpp#1468). If the child-process coordinates which are set there look wrong, the issue is probably with the parent-to-child transform matrix (usually with the code in APZ which computes it). If the child-process coordinates look right, the issue is more likely during the event dispatch in the content process.