When XAMPP 7.0.5 is started for the first time, the XAMPP control panel window appears at the top-left of the screen and under the Windows taskbar when the taskbar is position at the top of the screen. In order to move that window from under the taskbar, I either have to reposition or resize the taskbar or set the taskbar to auto-hide.
Even after repositioning the window so that it doesn't overlap the taskbar, the window can reappear under the taskbar if the user has a shortcut item pinned to the taskbar linking to <drive>:\XAMPP\xampp-control.exe and the user invokes the control panel using that shortcut (instead of using the icon in the system tray). This appears to recur until the user uses the Quit button in the window to exit the window (as opposed to the X button).
It would make more sense to initialize the control panel window in the center of the screen instead of the top-left. That would presumably fix this issue and potentially others with taskbars positioned at the side of the screen or those which have been expanded to multiple rows.