Toolbar does not go full width on 4K

[moxy-bc]

The Arduino toolbar does not display full width when maximized on a 4k screen. See this screen-shot.

[facchinm]

@TheBetaFruit commented:

When using a 21:9 Ultra-Wide Monitor (e.g. the popular LG 34UM95, resolution = 3440x1440px), the upper turquise menu bar of the Arduino IDE is too short in full-screen mode and therefore centered with two ugly grey areas besides it.

It would be nice to fix this by making sure the menu bar stays left-aligned while expanding the turquise area to the right, fitting any screen width.

[cmaglie]

Fix will be available on the next release 1.8.4