"focusable" for non-floating (split) windows

[cortesi]

Problem

The "focusable" attribute is explicitly ignored for non-floating windows. For example, here is the code for going to the next/previous window, which ignores focusable==false unless the window is also floating:

neovim/src/nvim/window.c

Lines 355 to 374 in 7e65f37

	if (nchar == 'W') { // go to previous window
	wp = curwin->w_prev;
	if (wp == NULL) {
	wp = lastwin; // wrap around
	}
	while (wp != NULL && wp->w_floating
	&& !wp->w_config.focusable) {
	wp = wp->w_prev;
	}
	} else { // go to next window
	wp = curwin->w_next;
	while (wp != NULL && wp->w_floating
	&& !wp->w_config.focusable) {
	wp = wp->w_next;
	}
	if (wp == NULL) {
	wp = firstwin; // wrap around
	}
	}
	}

I'm working on an addon that adds "companion windows" for certain functionality where non-focusable, non-floating windows would be really useful. I note that it's possible to set the focusable flag on non-floating windows without error, and the fact that focusable only applies to floating windows is not mentioned in the docs.

• I'd be happy create a PR to change window navigation to respect the focusable flag unambiguously. Can anyone who knows the project well think of a reason why this shouldn't be done?
• If we can't fix the behaviour, I think we should at least fix the docs to be explicit about this. We should also consider returning an error when the focusable flag is set on a non-floating window, as we currently do for other attributes that are floating-only (borders for example). I'd be happy to create a PR for this too.

Expected behavior

When the focusable flag is false for a non-floating window, I expect window navigation commands to skip the window.