After installing the beta (18.11) I got a green border around each dialogue.
Nothing to do with NextSTART, I can assure you. Looks more like a WB vs. NextSTART issue?
I was able to convert my book folders to stacks and taking my cursor off the Drawer it closes and the stack remains until you click on something else.
That's actually a bug lol. The Drawer is not supposed to close automatically until you close the stack.
It works on the Drawers but not on the workshelf. I thought it was supposed to work there too. I can browse but not convert to stack.
Quick tutorial:
The Shelf (tabbed dock) supports multiple different types of tabs: the Regular tab type is like the tabs in OD tabbed docks, when you add a tab of type Regular to the Shelf you can do with it everything you can with shortcuts in a dock (add modules, internal commands, Grid Stacks, order the icons however you want via drag & drop, etc...)
All the other tab types are very different (you should intuitively understand what each tab type is by its name): the Folder tab type, for instance, allows you to show you the contents of any folder in your hard drive as a tab in the Shelf. Not only that, you can drag & drop files into it, and those files are automatically copied or moved into the folder in the hard drive. Likewise, you can drag & drop files and folders OUT of the folder tab.
Be very careful when manipulating a Folder tab, because unlike what happens with Regular tabs that only hold shortcuts to files or applications, on a Folder tab you are directly manipulating the actual files inside the folder (a Folder tab acts like an Explorer folder in this sense)! So, if you delete a document file from a Folder tab, you are deleting the actual document, not some virtual shortcut to it!
Now, on a Folder tab you can only sort the contents by name, date, type and size, just like with folders in Explorer - you cannot freely organize the contents like you can on Regular tab types. In the same manner, you can only add file system objects to it (files, folders, etc..) - you cannot drag items specific to the Winstep application (like modules, internal commands, Grid Stacks, etc) into it because those are not recognized or even understood by the Windows file system.
There are many other tab types: for instance, the Desktop tab shows the contents of the Windows Desktop as a tab in the Shelf. This can be very useful to maintain a clean desktop and to quick access items on the Desktop: you tell the Winstep application to hide desktop icons, and then you launch/view those icons by opening the Desktop tab in the Shelf instead! Again, the Desktop tab in the Shelf offers full drag & drop support - you can even right-click-drag files and folders into it, so you are offered an option to either copy, move or create a shortcut to those files.
The Documents tab type shows the contents of your Documents folder. It acts exactly like a tab of type folder pointing at the Documents folder in your hard drive (more on this later for you to understand how it is related to your inability to convert folders in this tab into Grid Stacks, like you could in the Drawer).
Some of the tab types reference special virtual folders in Windows: for instance, the Control Panel tab type shows the contents of the Windows Control Panel. The Drives tab type shows the contents of the My Computer folder (normally your drives plus a bunch of other stuff). These type of virtual folder tabs - again just like the real thing in Explorer - do not allow you to drop items into them, although you can drag items out of them.
Other tab types have very specific functions and some do not support drag & drop at all. For instance, the Apps tab type shows all the installed UWP apps on your Windows 10 system. The Themes tab shows all your installed Winstep themes, which you can then apply simply by clicking on the thumbnail. The Recent Documents tab shows your <x> most recent documents. The Most-Used tab type shows a list of your recently launched and most used applications. You can even add a tab to the Shelf that displays all the icons in the Windows System Tray! 
As you can see, what you can and cannot do on a specific tab in the Shelf depends on the type of the tab! At the same time, this should allow you to understand how powerful and flexible the Shelf really is - it is definitely not a toy, although you can still have a lot of fun playing with it. 
Now, and this is the important thing: Drawers and Grid Stacks are variations of single tabbed Shelves, they just behave differently. Therefore, everything you can display on a Shelf, you can also display on a Drawer or a Grid Stack. The major difference is that while a Shelf supports multiple tabs, Drawers and Grid Stacks can only host a single tab - you can say they are that tab.
This tab can still be of any of the different types of tabs that a Shelf supports. Therefore you can have Regular Grid Stacks, Control Panel Grid Stacks, etc, and, of course, the type most normally associated to Stacks: a Folder Grid Stack. Same for Drawers.
Now, wrapping back to your issue: a Grid Stack is a Winstep object. As such, it can only be placed in docks, in tabs in the Shelf of type Regular or in Drawers and other Grid Stacks also of type Regular.
You cannot convert folders in your Documents tab in the Shelf into Grid Stacks like you can in the Drawer because the Documents tab is a Folder type tab and therefore part of the Windows file system (which, again, does not know how to handle Winstep Grid Stacks). Likewise, you could convert folders in the Drawer into Grid Stacks because that Drawer is of type Regular.
I hope this explanation helped a bit and didn't make you even more confused instead. 
