CSSTUDIO-3429 (1) Restore label height fix and (2) Fix Byte Monitor widget

[abrahamwolk]

This pull request:

1. Restores the label height fix (as reported in Label height is ignored if the font size is larger #3533)
2. Implements a fix to the Byte Monitor widget bug described in CSSTUDIO-3325 Bugfix: Make labels of Byte Monitor widget visible when placed alongside a Label widget inside of a tab of a Navigation Tabs widget #3518

The background for this pull request is described in issue #3533.

This is still a work-in-progress. In particular, more testing needs to be done, and perhaps the fix can be improved.

[abrahamwolk]

As far as I can see in my testing, the current implementation in this pull request fixes the bug in the Byte Monitor widget, and I consider the pull request ready to be merged.

@rjwills28: You mention in #3533 that you can reproduce the issue with other widgets. Perhaps other widgets need should be fixed as well. I have, however, not been able to reproduce it with the Combo Box widget. Do you have a way of reproducing the issue with other widgets?

[abrahamwolk]

After more testing, this pull request (and in particular commit 7c092bf) does lead to problems in the Navigation Tabs widget. If a Byte Monitor widget or a Linear Meter widget is part of an OPI that is displayed in the Navigation Tabs widget, then in perhaps 10-20% of the times the tab is opened, the widget will update very seldomly, perhaps at 20 or 30 second intervals or so. This can be observed by connecting the widget to a simulated PV of the form sim://ramp(1,10,1).

I have added back the tag wip to the pull request.

[abrahamwolk]

Sorry: I jumped to my conclusion too quickly! In particular, the commit 7c092bf is not the cause of the observed issue.

Rather, it seems to be the Waterfall Plot widget that was merged in #3520. I only observe the slow updates on the Byte Monitor and the Linear Meter when the Waterfall Plot widget from that pull request is running (the Waterfall Plot widget in another display than the one where the bug occurs!). The bug seems to disappear again after #3544. I don't have an explanation for this.

I remove the wip tag again from this pull request, since it seems to work well when I test it after I merged the current master branch into the branch of this pull request.