Shell mode show a new prompt when switching windows

[Benjamín Buccianti]

This is basically the problem. When I use my zsh theme frisk from shell mode, 
whenever I switch windows it disable the last prompt and show a new one causing 
the accumulation of blank prompts. 

When I disable the theme on zshrc this don't occur. I'm thinking that something 
is going on with the definition of the frisk prompt but I don't know how see 
what's really going on under the hoods.

Any idea to solve this?

Thank you,
Benja