Hmm. I can see how that could trigger, although you have to be kinda lucky (or slow) to end up at the right pixel.

I'm adding pointer barriers to the panel, so that it will be easy to hit the corners on the primary monitor. However, i don't think we want to add barriers in each monitor corner, for instance that would make it hard to enter the primary monitor.

I think we should only add hot corners on monitors that have a natural top-left corner, like the leftmost monitor, or a non-primary monitor in a layout like:


corner -> +-------------
          |            |
+---------+            |
|=========|            |
|         |            |
|         |            |
|         |            |
+---------+------------+

I was aiming for the status/session-applet and happened to slow the movement down just a bit early. For reference the setup was like this:

          unexpected hot corner
          ↓
+---------+-------+
|=========|       |
|         |       |
|         +-------+
+---------+


Your solution sounds good.

Created attachment 183712 [details] [review]
Only add hot corner for primary and "top left" monitors

To avoid having hot corners that accidentally trigger when e.g. trying
to hit the panel on the primary monitor we add hot corners only to
monitors that are "naturally" top left (top right for RTL).

For instance, we'd like a hot corner here:

corner -> +-------------
          |            |
+---------+            |
|=========|            |
|         |            |
|         |            |
|         |            |
+---------+------------+

But not here:

          unexpected hot corner
          ↓
+---------+-------+
|=========|       |
|         |       |
|         +-------+
+---------+

Review of attachment 183712 [details] [review]:

Seems probably right to me, especially since we won't have barriers on a lot of sstems for GNOME 3. I think we haven't really solved the question of how you use the overview in a multihead configuration - if you have to mouse across two monitors to get to the overview (or interact with it after bringing it up with a hot key) that's pretty hard. Maybe it will make sense to have hotcorners on each monitor and bring up the overview on the monitor where you activate it.

Patch looks good to commit, except for one small style point.

::: js/ui/main.js
@@ +502,3 @@
+
+
+        let haveTopLeftCorner = true;

This naming is sort of confusing, but don't have a suggestion otherwise, so OK.

@@ +509,3 @@
+        if (St.Widget.get_default_direction() == St.TextDirection.RTL) {
+            besideX = monitor.x + 1;
+        }

Excess {}, generally would prefer if this was written symetrically instead of overwriting the LTR case with the RTL case.

Attachment 183712 [details] pushed as 70ae700 - Only add hot corner for primary and "top left" monitors