To the best of my knowledge, all the popup and other functionality is controlled by scripting. Of course, your mileage may vary based on different browsers, browser versions and browser behaviors, but by and large there are no real limitations you might see because a topic was opened using a context sensitive call.
Thank you. So, you mean that I can manage the final output design & behavior through CSS?
Uhhh, the initial thread was talking about CSH (Context Sensitive Help) and now you are asking about CSS (Cascading Stylesheet Specification).
I'm not sure exactly what you are asking because Output Design and Behavior could be influenced via CSS, sure. But CSH is just a way of connecting the help to an application. So I'm a bit confused.
If you want to customize the popup, you will need to use jQuery modal box, and use CSS to edit its style in the way you want to.
This topic illustrates different samples of Robohelp CSH and how to open it in a popup or a new tab:
"window.open('" + Label + "', 'popup_window', 'width=1024,height=768,left=100,top=100,resizable=yes');"
This shows comprehensive examples:
If you need an alternative turn-key solution that works the same but is very simple and customizable let me know (I can share it with you).