Non-modal/Modeless Popup or Window

The wording predates the ability to have tabs in browsers. Then at one point you could choose to open the new windows as tabs instead. Now everything opens as tabs by default and you have to manually open new windows. However, you can use javascript to force a new window, especially if you want to specify a custom size.

See here for details: https://developer.mozilla.org/en-US/docs/Web/API/Window/open

If you have friendly developers, the should be able to develop something for you.

I doubted there was a way to open a nonmodal popup or window, but I tried. I'm just trying to satisfy the stakeholders. Thanks!

I needed to be clear on what you meant. I would not expect many people to know that you can drag tab down and a new intance of the browser will open, I for one did not. Also I'm not seeing how that helps as it just puts the topic with the popup in another instance of the browser, rather than just another tab. So moving on from that, you said, 

I have been using the drop-down to set the hyperlink to open a new browser tab, although the feature says it opens a new browser window. The user must pull the tab off to create a new window.  

I created a popup in a topic, set it to New Window. That opens a new tab rather than a new window.

Regardless of all the above, other than some home-brewed solution, there is nothing in RoboHelp to do what you want, to the best of my knowledge.

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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.

You know how you can drag or pull a tab off your browser to make it new window?  I do that all the time.  You merely drag and drop a browser tab to pull it off the current browser window to create a new browser window.  Your words and mileage may vary from mine. 

I'm not sure what you mean by The user must pull the tab off to create a new window. If you mean close the new tab, yes that is the downside.

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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.

I have been using the drop-down to set the hyperlink to open a new browser tab, although the feature says it opens a new browser window. The user must pull the tab off to create a new window.  This is not what stakeholders wanted; they wanted a non-modal (modeless) window or popup.  So, I will give them the news that it will not be possible without requiring the user to pull the tab off. Thanks for confirming what I suspected!

As I understand it modeless means a popup that can be left open. That is not how RoboHelp's popups work so you would need your developers to script something for you and I can't be sure it would not have some side effect.

When you create a link to another topic, there is a dropdown that enables you to open the target in a new window.

________________________________________________________
My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.

Not really sure what you mean by non-modal or modeless popup - your links can use that "New Window" property in them, but I thought that its behaviour was governed by how the user has their browser set up.