The screen transition button will switch to a display a different screen when it is pressed. This is done by specifying the screen number as pictured below.
Double-clicking the button in the ComfileHMI Editor will open its properties window. From there the screen to transition to can be selected.
Using a variable for the screen number provides the ability to make the screen to transition to modifiable at runtime.
The following video illustrates how to use the screen transition button.