left panel: reverted menu icon scale to match item font size

[h0lg]

Fixes #9964

Screenshots (Before / After)

I agree that the maintainer squash merge this PR (if the commit message is clear).

✒️ I contribute this code under The Developer Certificate of Origin.

[h0lg]

Just rebased on the master.

[h0lg]

@RussKie I've reverted the ImageScalingSize of both the leftPanelToolStrip and menuMain to 16x16 and the designer-generated lines vanish on save. My forms designer seems to be opinionated about the sizes though and resets them to 20x20 upon re-opening. That must be how those lines slipped in. And you were right, 16x16 seem to render just the same icon size as before. But so does 18x18. In other words, the difference between 18x18 and 16x16 is not visible to me.

[pmiossec]

My forms designer seems to be opinionated about the sizes though and resets them to 20x20 upon re-opening.

@h0lg I think that the reason is that you have a display scaling different than 100%. And in this case, every time you have to use the winforms designer, you should launch VS with the /noscale option. See https://github.com/gitextensions/gitextensions/wiki/Guidelines%3A-UI-design

[RussKie]

See gitextensions/gitextensions/wiki/Guidelines%3A-UI-design

Unfortunately, this guide is only true for .NET Framework, and it is not suited for .NET. The goldbar has been removed because the out-of-process designer doesn't work in hdpi scenarios. That said, the goldbar will be back in VS 17.3p1, and /noscale should be working for .NET apps as well. Until then, the designer should be run on monitors at 100% scale factor.

[RussKie]

Thank you