Key focus does not follow the mouse pointer and click smoothly : Windows 10 host, linux guest, guest addition is install.ed

[ci-zephyurus]

I am using VirtualBox version 7.0.20 r163906 (Qt5.15.2) under Windows 10 Pro 22H2, OS build 9045.5011 and the guest is Debian GNU/Linux. (uname -a output is

Linux ip030 6.10.4-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.10.4-1 (2024-08-12) x86_64 GNU/Linux)

Since this spring, I have noticed that the key input focus does not automatically follow the mouse cursor movement outside the VirtualBox windows.

For example, I am editing a file in GNU Emacs in the linux guest inside VirtualBox running on Windows 10 pro. Then I want to input something to the windows application such as firefox somehow. I move the cursor to the input field of firefox window under windows 10 pro and click the mouse button to indicate that the next key input should go there.

Problem is that sometimes nothing happens when I try to type into the input field of the native windows 10 application.

Sometimes and not always. This makes it a bit difficult to figure out what goes on. The problem seems to happen more often when there is a serious workload inside the Guest linux such as building the mail client thunderbird from source.

If I realize that somehow the key capture is not released by virtualbox + guest linux addition for my guest linux after I moved the mouse cusor outside the virtualbox window and clicked the mouse button somewhere OUTSIDE the virtual box window, and INTO the input field of a window application, then I will use the Right Alt key to release the key capture by virtualbox. However, virtualbox handled the smooth key input focus movement simply by my moving the mouse cursor outside the VBox window and my clicking on an input field outside the VBox window before the spring of 2024, I think. So I often do not realize the problem lies with VirtualBox not releasing the key capture, and not the problem of the native Windows application to which I would like to enter characters. So it is quite awkward until I somehow recall the problem of VirtualBox.

The scenario goes like this. Suddenly I realize that nothing happens when I try to type something into Windows applications. Then after scratching my head for a while, I pause to figure out what went wrong. Only then I realize this is the dreaded virtual box symptom I have experienced from time to time since this spring and I hit Right ALT key. Then all is well.

But this should be smooth sailing. I should not have to press Right ALT key.

I tried to see if similar symptoms have been reported, but I am not sure if recent posts exist.

I do have guest addition installed. So that is more puzzling to me. Maybe the guest addition has become buggy? (Or Windows update introduced some subtle Windows API changes, etc.)

I have used VBox 7.0.22 and experienced the same bug and reverted to 7.0.20 to see if the situation improves. Nope. This is why I am using 7.0.20 now.

Any pointers to fix this bug will be appreciated.