Here’s another approach that would accomplish what you looking to do without too much ado:
⌘X to cut the equation text.
- Press the shortcut to split at the cursor point and probably just hit
Esc to terminate rename. Hit
↑ to select the first segment.
Project ▸ New From Template ▸ (equation). We get a new item as a sibling below the current.
⌃⇥ to shift over to the editor.
⇧⌥⌘V) to paste what we cut in step 1.
The nice thing about this approach is that it is fully keyboard and menu command accessible, meaning automation like Keyboard Maestro (Mac) or AutoHotKey (Win) can step in and make this pretty much “one click”.
Now as to the feature request itself: the problem as I see it is that there are multiple things going on here that do not have a native single-click solution (let alone all at once):
- We are splitting the text twice, both before and after the selection range, resulting in three items.
- One of the items does not split in the fashion it ordinarily would (inheriting the attributes of the item it was split from), but instead adopts attributes from something else in the binder (a template).
The problem isn’t so much that your idea isn’t addressing something useful—I definitely see what you are going for here—but rather that I’m having a hard time thinking of an elegant solution to addressing how any of the above happens with any more elegance (or less keyboard/clicking events) than the existing methods.
A three-way split? Sure, though it might be a mouthful to try and explain the result in a menu command, that is at least conceivable—and such things really do need to be explained well since this is one of those few things you can do in the editor that you can’t always as easily undo.
But how to have one (or more, I guess?) of the three split items “know” that it should import metadata attributes from a particular other binder item or template? Sure you’re thinking of the middle document being split off in this particular use case, but why not the first or third, or even all three? And how do we designate which item to pull attributes from?
Further, there are complications with using a template to stuff existing text into, or to in other words, apply a template to an existing item. What happens if the template has sample text in it already? I suppose we append or prepend it (neither is clearly better to my mind), but that will probably require further action on your part to clean up the result.
You might think metadata is more straight-forward, but is it? In this case here, there might be important attributes about the item we’re splitting off from that we might want retained. Should we split normally, so synopses and notes and keywords and other ephemera get applied to split 2 and 3, and the overwrite anything conflicting that the template assigns?
And what is conflicting? What is default in this case? For some things there may be clearer answers, but is deleting all keywords because the template has no keywords appropriate and expected? Should the action be essentially like a macro from New From Template + Add new item below with stuff + Select both and Merge? That’s a result that is in my opinion noisy for the sake of safety rather than ideal.
I don’t know, I just have a lot of questions about how this would work in practice. We might program it to work very specifically the way you want (only the middle item gets a template’s attributes, template overwrites everything in the Inspector, etc.), but I bet you if we did that we’d just get more feature requests to make it more flexible—which means more interface, and less elegance.