Water repellent for shower
I have 3 glass panels in our shower recess and because the window is where it is, the light shows up any dried water spots on the glass. I now use a car product by Stoner called Invisible glass. It's a rain repellent and a water fluid additive. I cleaned the glass with vinegar and water dried it off then sprayed diluted invisible glass, and wiped it gently off with a clean cloth. I've done this once in six months. After a shower i just squeegie the screen.
15ml to 500ml water in a spray bottle, it comes in a 300ml bottle, i bought it from Super Cheap.
WD 40 also works