I'm not quite sure what you mean, but my tool Jetstrap (http://jetstrap.com/) has grid support. You can drag in a grid row and then drag in grid columns. The UX on the grids isn't quite where I want it yet though.
a WYSIWYG editor may not suitable for layout manager. The idea is separating content from the template (layout/grid). However Bootstrap Live Editor also provides a basic grid insertion function as in the demo, which can be used to insert multi column text, etc.
there is definitely a need for this, but I wouldnt necessarily approach it that way. For example, jQuery UI does have widgits that are resizable to a grid, however its a pixel resize sort of thing. This isnt so bad if you dont mind dealing with absolutely positioned content, but it gets very messy very fast if you wanted an 'editor'. I think if we could get a plugin that does this independently of bootstrap, and works sanely when you think about things floating and moving around in a browser, think draggable/portlets, then you'd have definitely found a new holy grail. However portlets require certain source expectations as well, and it's just not setup for a grid. Anyway, there are many expensive enterprise CMSes that don't even have this for their author views for content pieces, and it would be a huge feature I think.
An approach I'd like to try is allowing the template designer to expose a certain amount of grid changing freedom. I'd also like to experiment with content types that have a render method parameterised by width (and possibly height).
What if I use it as a online WYSIWYG HTML editor? If I create a table and then copy paste the HTML code into not BootStrap based webpage like Blogger, will that work?
I think it should work if I have not included special Google webfonts.
Just need to disable the "Bootstrap Snippets" button, and you got the Editor for non bootstrap content/purposes. "Bootstrap Snippets" button is used to insert Bootstrap's elements (Hero Units, Header, Well, Labels, Badges, Buttons, Icon glyphs, Alerts, etc). Google webfont feature is also optional.