Why can't I "split" off a window from the main? Why only panels?

[L A Walsh]

I had maybe 4-5 panels open on a file but couldn't really get the
display the way I wanted... Alot of GUI's have options to dock a
window or panel in 1 main window, as well as the ability to split the
window off so that it floats independently. How difficult (or would it
be difficult) to do this with gvim?

The split window would be part just as much a part of the initial
vim-instance that spawned it -- just as split windows are now.

Only difference is that a detached window could be moved independently.
Given the number of GUI's that implement such a feature it doesn't seem
like it should be too difficult in gvim....

Possible? Doable? If not, why not? How would it be different from
a popup in any other gui?

Thanks...
Linda