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Cannot utilize CTRL+WIN+F24 to toggle PTP on/off state at Lock screen RRS feed

  • Question

  • Hi,

    I am developing a feature that using a combination key, Fn+F2 keys, to turn on/off the Precision Touchpad (PTP).

    According to the MSDN document "Legacy Touchpad PC Settings Opt-In"(https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/windows-precision-touchpad-legacy-touchpad-pc-settings-opt-in) , it mentioned "Any custom hotkeys that were used to change settings (for example, enable/disable) should be non-functional if they impact any opted-in setting. Windows provides an inbox hotkey for enable/disable control (CTRL+WIN+F24), which an OEM can support ."

    So, I developed a filter driver which can send CTRL+WIN+F24. When Fn+F2 keys are pressed, the Embedded Controller (EC) sends a specific keyboard Scan Code (e.g., 0xE055) to my driver, and my keyboard filter driver sends CTRL+WIN+F24 to OS. It works well to toggle PTP on/off by Fn+F2 keys.

    The question is, CTRL+WIN+F24 works when user has logged in or at Logon screen, but doesn't work at Lock screen. When user locks the computer, or sleeps, or hibernates, the first page when resumed is Lock Screen. If you click the mouse or keyboard, the Logon Screen shows to let user input the password.

    It is interesting that Win10 OS regards the CTRL+WIN+F24 as common keys at Lock Screen. When I press Fn+F2 keys and driver sends CTRL+WIN+F24 to OS, it simply switch the screen from Lock Screen to Logon Screen. As if I make any keystroke.

    As a result, the PTP state keeps the same when I press Fn+F2 keys at Lock Screen. I must switch to Logon Screen to let Fn+F2 keys work well. I have no idea why Win10 OS designed to ignore CTRL+WIN+F24 at Lock Screen. The document "Legacy Touchpad PC Settings Opt-In" didn't mention that.

    Is it a code bug? My test environment is Win10 RS4 RTM build 17134.

    Friday, August 10, 2018 6:30 AM