An alarm can be used to wake up the HMI when it is in screen saver mode. The screen saver feature just changes the Base Window ID to the ID number of the screensaver window (80 by default, you can adjust this in the system parameter settings). The Base Window ID is stored in system register LW-9050.

An alarm can be used to write the base window ID of the window you want to display when it triggers to LW-9050, so that window will be displayed even while the screen saver is showing.