Affected versions

• 71.0b4, 72.0a1 (2019-10-23)

Affected platforms

• all can benefit;

Steps to reproduce
Only one of the prefs is set on true:

• devtools.netmonitor.features.requestBlocking
• devtools.netmonitor.features.search

1. Launch Firefox, Open DevTools, Netmonitor;
2. Access any webpage;
3. Enable the Search or Blocking panel(s) if not visible;

Actual result

• section header spans over half the available width, giving the impression that something is missing;

Enhancement suggestion

• have the Blocking/Search section headers expand over all the available space if only one displayed;

Additional notes

• attached recording to better illustrate the issue;
• might be the same case for the Section in the Debugger tool, but considering that the Search and Blocking panels might not be released at the same time it's something that might be worth taking into consideration here.

Since the plan is for both the Blocking/Search features to be enabled at the same time on the RC builds this will not be an issue.
With the current Beta & Nightly builds, each feature needs to be enabled by a pref in order for the issue to become noticed.

Closing the issue for now, since there is no real impact and there are other more important issues that need attention.