[Logging] Expand/collapse icon only appears when its hovered, not focused

[lostintangent]

Repro Steps:

1. Open up this URL
2. Launch the Glimpse client
3. Select the request which corresponds to the /create route
4. Click the area where the expand/collapse icon would appear on the first log message. As an aside, it appears like this icon is still interactive for single-line logs, despite being hidden.
5. With the expand/collapse icon focused from the previous step, hit the <TAB> key.

Expected: For the triangle icon to appear when it is focused via the keyboard, since without, it's unclear what hitting <ENTER> should do until you try it.

Actual: A "focus ring" appears to indicate where focus is it, but the expand/collapse triangle doesn't appear unless you also actually hover your mouse over it.

I tend to prefer a keyboard-driven workflow, so having these kinds of interactions work smoothly go a long way.

[mike-kaufman]

This is a side-effect of a temporary workaround on some perf issues (See https://github.com/Glimpse/Glimpse.Client/pull/239). The long-term perf fix (virtualizing log messages display) should eliminate this work-around & eliminate the issue. We should probably keep this open until the perf issues get resolved.

it appears like this icon is still interactive for single-line logs, despite being hidden.

@philliphoff checked in a fix for this in M15 (see https://github.com/Glimpse/Glimpse.Client/pull/224)