Thank you for the links and responses. I'll study them and come back if necessary.

Re: left/right margins, headers, etc.: I wasn't referring to the editing mode, but as a part of my mock-up.  I set three sub-artboards with on-click opening. Each open/close functions individually, but if I try to open another element with one already open, the first one closes.

Hello Kostem, 

Nice to know that you are interested in Mockplus. 

Here are our answers for your questions: 

1).About tutorials 

All the tutorials of Mockplus RP is listed here: https://help.mockplus.com/p/401

Or you may also go to our Youtube channel to watch all video tutorials: https://bit.ly/3OjymL4

2).About the differences between 'panel' and 'content panel'

They are made for different design purposes. 

Panel is a container that allows you to put all things you need, like a card format content, a popup, a table, a product display section and more, and use them all as a whole. 

Well, Content panel is often used to help you present switchable content. This tutorial can help you learn more details about how to use it: https://help.mockplus.com/p/466

3).The difference between artboards and panels

To know the difference, you may first learn about our sepcial "Main-artboard + sub-artboard" suite, which allows you to present all important content on the main-artboard, and put out all popup, altert, notification or other dynamic content on the sub-artboard. So, when you are editing the main page content, the popup content will no longer cover any content of your main page. 

And this popup making video can help you know differences between them clearly: https://bit.ly/3xB5wyO

4).About the left and right margin 

If you mean the left and right panel in the editing mode, you may now try to show or hide them like this: Main menu > Views > Show left panel/Show right panel/Enter full screen

Please let us know if this helps you.

Of course, if you do have any other problems, please contact support@mockplusapp.com