How can I open a widget by clicking a button in the sticky bar?

[Alocard]

I have 2 apps: "Easy Sticky Add To Cart"(app 1) and "Slide Cart"(app 2). App 2 opens a widget when you add something to your Cart:

App 1 is a sticky bar on the bottom of the page: 

My question is: Is it possible to open the Widget when clicking on the Button in the sticky bar?

I have the possibility to add custom JavaScript in App 1, but cant change the code.

Thank you for your help in advance.