This prevents the editor from synchronously redrawing in specs with
cursors in invalid locations. Markers are always updated under the
hood before a change event is emitted from the Buffer or DisplayBuffer.
We still wait to trigger marker observers, but if their position gets
read, it is up to date.
When the font size changes and the editor is detached, it schedules
itself to be redrawn the next time we're reattached rather than
updating the display in a detached state.
Detached display updates worked in the past because we didn't need to
be on the DOM to determine horizontal and vertical positions once we
had calculated dimensions once. So it worked to temporarily attach
the editor when calculating new dimensions, and then continue updates
even when it was detached. That now breaks because we can't ask for
pixel positions if we aren't on the DOM.
When translating a logical screen position (columns/rows) to a pixel
position, the editor now builds a temporary version of the line for the
given row. It then uses the DOM range API to insert an empty range
at the correct text node and offset for the given column and determines
the left position based on its clientRect.
Depending on the speed impact, we may want to optimize this by
recycling the existing line node if it exists on screen rather than
building a new one every time. We will still have to build one if the
line we're moving to isn't on screen yet. We could also increase the
chances of the line being on screen by autoscrolling to the vertical
position first, and *then* calculating the horizontal position. Lots
to explore here.
Allowing root view to be focused was stealing focus away from the
editor whenever a click event made it to the root view. This unnecessary
switching of focus was interfering with the ability to drag tabs.
But if RootView can't be focused, focus ends up being returned to the
document body when there are no focusable elements. This would be fine,
except for the fact that we frequently bind global events on root view,
and so they aren't triggered when events are triggered on the body. We
could just bind all global events on the body, but this would require
us to always attach elements to the DOM during specs, which is a serious
performance killer in specs.
The workaround is in the keymap. When the keymap handles a key event
that was triggered on the body, it triggers the corresponding semantic
event on the root view anyway, so from the event perspective, it's as
if the root view actually had focus. The only place this might fall
down is if someone wants to capture raw key events. But that's the
keymap's job anyway, and we maybe add a hook on the keymap if such a
need ever arises.
