Error signal red square really too small

[albu77]

• VSCode Version: Code 1.11.1 (d9484d1, 2017-04-06T13:58:12.954Z)
• OS Version: Windows_NT ia32 6.1.7601
• Extensions:

Extension	Author	Version
vscode-javascript-snippet-pack	akamud	0.1.5
project-manager	alefragnani	0.13.2
vscode-great-icons	emmanuelbeziat	1.1.44
beautify	HookyQR	0.8.8
typings-autoinstaller	jvitor83	1.2.0
phpmd	linyang95	1.1.4
gitignore	michelemelluso	1.0.1
vscode-todo-parser	minhthai	1.8.7
debugger-for-chrome	msjsdiag	2.6.0
bootstrap-3-snippets	wcwhitehead	0.0.9

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Steps to Reproduce:

1. In a js file for example type a syntax error
2. red square in the vertical slider area is really difficult to see
   COULD it be a little bit bigger
   
   and More, text of the editor could overwrite it depending on the line length and screen width
   Two small problems in one...
   

[alexdima]

The vertical scrollbar can be made wider via the "hidden" setting (a VS Code restart is necessary):

    "editor.scrollbar": {
        "verticalScrollbarSize": 20
    },

[alexdima]

I will push a change that improves the contrast for warnings and errors on the high contrast theme: