This behavior is by design. When we use any tool bar application, the windows explorer does release the reserved space for the Appbar when it is docked and undocked to the top of the screen. In Windows 10 and later Microsoft introduced design change for Explorer to reset Workarea on receiving WM_SettingChange along with Seamless setting workarea for Appbar if not set already when it receives WM_SettingChange will result in recursive setting of workarea by Explorer and Seamless. In order to support Appbar functionality in Windows 10 Seamless needs to undergo design changes to support the changes introduced by Explorer design change, a feature enhancement request to be created to fully support Appbar functionality in Windows 10.

For additional information, see the Microsoft article -- https://support.microsoft.com/en-us/help/4014104/applications-calling-the-systemparametersinfo-function-with-the-spi-se

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Problem Cause

This behavior is by design. Current design of seamless doesn't support Appbar due to windows explorer design change by Microsoft introduced in Windows 10 and above. We have an enhancement request created to support this feature in the future.