Show table scrolling a bit clearer - ux fix

[ghost]

This relates to this comment: #4618 (comment)

Large screens (non-scrolling mode)

Smaller screens (scrolling mode)

p.s. I can't take screenshots of the mouse cursor so I added them in - that's why they look a big strange. But you get the basic idea.

[ghost]

@LukeTowers @bennothommo Something seems wrong with Travis, please can you look into it. The last three PR's all failed. This is the error msg:

There was 1 error:

1) UpdaterTest::testClassNameGetsParsedCorrectly

ReflectionException: Class October\Rain\Tests\fixtures\Database\SampleClass does not exist

/home/travis/build/octobercms/october/vendor/october/rain/tests/Database/UpdaterTest.php:15

[bennothommo]

@ayumihamasaki2019 Travis CI should be fixed now, on your next commit. :)

[ghost]

@bennothommo Perfect, thank you!

@LukeTowers All done, pls re-review.