Fix scrolling list (SQL Lab Query Search)

[tomdewildt]

When the content in the Query Search table is larger than the viewport no scrollbar appears. Leaving the user unable to scroll.

Expected results

A scrollbar appears and the user is able to scroll.

Actual results

No scrollbar appears and the user is unable to scroll.

Screenshots

How to reproduce the bug

1. Create 15 or more querries.
2. Visit the Query Search page.

Environment

• superset version: master
• python version: 3.6.7
• node.js version: v9.11.2
• npm version: 5.6.0

Checklist

Make sure these boxes are checked before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

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[margrathea]

If you add overflow: auto to the scrollbar-container div in your browser than you're able to scroll again...

[protok]

If you add overflow: auto to the scrollbar-container div in your browser than you're able to scroll again...

This is just a quick hack, this needs to be fixed somewhere in the stylesheets.

[tomdewildt]

If you add overflow: auto to the scrollbar-container div in your browser than you're able to scroll again...

This breaks other UI elements that also use the .scrollbar-container class