Learning about splitscreen in construct 2

I try to combine the split screen from Anggi's work into my work.
After several trying of understanding, copying and pasting the code into my work, finally I get the split screen feature into my work.
However, there are still some bugs with the split screen in my work which are:
- if player 1 (upper screen) reaches bottom of the map, he will vanish because of the canvas covers him up
- if player 2 (bottom screen) reaches top of the map, the bottom screen size will reduce itself