I have a terrible, terrible theory about this.

I think there are two things at play:

1) The cursor is "redrawn" even when not actually visible. This is not too hard to fix with a bit of a hack in Textfield::UpdateCursor().

2) The cursor blink invalidates the area under the cursor, which necessitates redrawing every view that intersects that area - ie, the BubbleFrameView for the bookmark bubble itself. There's no easy way around this, since Views has no way to know that the cursor blink won't draw half transparent or something and let the lower Views show through. Probably the easiest way to fix this is to move the cursor into its own Layer, which we position at the right spot when we need it, since that way the Layer for the rest of the dialog won't get touched as it blinks.

Re: 2), I noticed that when I mouse over some controls they redraw themselves many times, which I believe is an animation from one fill color to another. When this happens the entire dialog does not repaint. Seems like if your theory about 2) is true, the dialog would repaint on each control repaint?

Some controls have backing layers, which mean that layers underneath them don't have to be redrawn. Textfields don't have backing layers (they use their parent's layer), but some like combobox have their own.

Actually, ick: comboboxes *sometimes* have a backing layer.

What exactly is a "backing layer?" Backing layer means one thing on the Mac, but I'm guessing it's not what Views means.

I'm not totally familiar with the philosophy of Views's design, so if putting the insertion point in its own layer is the best solution, you should of course do that.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1c77b2b6c04efe4e5d5d3ec5688616d65b8d0138

commit 1c77b2b6c04efe4e5d5d3ec5688616d65b8d0138
Author: ellyjones <ellyjones@chromium.org>
Date: Fri Sep 23 18:22:04 2016

Textfield: suppress cursor repaints when there's a selection

Without this, we do a considerable amount of repainting every timer tick.

BUG= 645262 

Review-Url: https://codereview.chromium.org/2322303002
Cr-Commit-Position: refs/heads/master@{#420667}

[modify] https://crrev.com/1c77b2b6c04efe4e5d5d3ec5688616d65b8d0138/ui/views/controls/textfield/textfield.cc
[modify] https://crrev.com/1c77b2b6c04efe4e5d5d3ec5688616d65b8d0138/ui/views/controls/textfield/textfield.h