Lines separating splitted terminal disappear when enable/disable menu bar

[alanlivio]

• VSCode Version:
  $ code -version
  1.37.0
  036a6b1
  x64

• OS Version:
  $ lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description: Ubuntu 19.04
  Release: 19.04
  Codename: disco

• Steps to Reproduce:

1. use integrated terminal at right and splited
2. enable and disable menu bar
3. the lines separating the splitted terminal disappear (see figures)
   
   

• Does this issue occur when all extensions are disabled?: Yes/No
  Yes

[Tyriar]

This appears to happen only when the first row of the lower split pane sits on top of the sash. I guess it's a problem with the internals of the pane not sizing correctly.

[jeanp413]

This is caused by the border-top in split-view-view from this css rule

vscode/src/vs/workbench/contrib/terminal/browser/media/terminal.css

Lines 83 to 86 in 2d3727b

	.monaco-workbench .panel.integrated-terminal .monaco-split-view2.vertical .split-view-view:not(:first-child) {
	border-top-width: 1px;
	border-top-style: solid;
	}

which isn't taken into account when calculating the height of the terminal

vscode/src/vs/workbench/contrib/terminal/browser/terminalInstance.ts

Line 432 in 2d3727b

const innerHeight = height - bottom;

Seems there's no easy way to get that value, maybe just always subtract 1 px from the total height const innerHeight = height - bottom - 1;