Intellisense box (Ctrl+Space) is broken in IE11

[T18970237136]

Hi,

I noticed a problem with the Monaco Editor in IE11, where the "intellisense box" (sorry, I don't know the correct terminology) doesn't show correctly in IE11.

Steps to reproduce:

1. Open the Demo Page and select TypeScript as language.
2. At the top of the file, type Math.
   Result in IE11 and Edge (OK):
   
   
   
   
3. Now press Ctrl + Space.

Actual (IE 11):

Expected (Edge):

Note that after pressing Ctrl+Space, even the other Intellisense window doesn't work again if you move the cursor somewhere and type Math. just like above.

We are using the Monaco Editor in the embedded WebBrowser control in a WPF which unfortunately is bound to IE11 instead of Edge, so it would be nice if Monaco shows correctly in IE11.

Thanks!

[sandyarmstrong]

There are a few ways to trigger this. The key for me seems to make sure that at some point the completion provider returns no results. From that point on, subsequent displays of the completion widget will result in invisible completion items (as displayed above).

Relatedly, on other browsers, if there are no completion results the widget will display "No suggestions." IE11 will not do this.

[sandyarmstrong]

I wanted to debug this issue but then ran into #97.

[sandyarmstrong]

Cool, turns out debugging works in Windows 8.1. In the scenario originally reported, the issue is that the tree child of suggest-widgets has display:none.

The message child of suggest-widgets has display:none when the suggest box works and when it malfunctions as described in the original report. But interestingly, it has a text child of "No suggestions" in the latter case. Even though monaco-list-rows is identically populated in both scenarios.

I'll keep digging.

[sandyarmstrong]

Yay, easy fix. In https://github.com/Microsoft/vscode/blob/master/src/vs/base/browser/dom.ts#L963, in the show function, just change element.style.display = null to element.style.display = ''.

I'll submit a PR.

[T18970237136]

Thank you!