material-ui

Example app: https://pp0o4x40p0.codesandbox.io/#/posts/13

I just copied the last tab a couple of times and you'll see a scrollbar at the bottom.
What I expected: that the Tabs component would be scrollable and the application not to crash.
I think this is because the Tabs parent width is implicit instead of explicit.
![2018-03-22_09-51-42](https://user-images.githubusercontent.com/621098

I upgraded to v4 and tried to load the page - I'm getting a "window is not defined" error. This is running on a NextJS project (SSR).

Expected Behavior

I followed the dashboard layout tutorial and following code fails as the config param is typed as (breakpoint: Breakpoint, config: Omit<TemporarySidebarConfig, 'id' | 'anchor' | 'variant' | 'hidden'>) => IEdgeSidebarRegistry; where the anchor is omitted

scheme.configureEdgeSidebar((builder) => {
  builder
    .create("uni