Should it vertical-align top?

@matmarex Wow, that's not an easy one. As long as we don't have an ability to know, when a scrollbar is visible and add for example another CSS class to change the oo-ui-indicatorElement-indicator correspondingly, this will always be sore on the eyes.

Where is this actually used?

In the second step of the new file upload dialog in VisualEditor (Insert → Media → Upload).

Since we control the height manually, it should be possible to add some CSS class in OO.ui.TextInputWidget.prototype.adjustSize if the scrollbar is being displayed.

Vaguely related: T116186

Probably not as common, but icons are also vertically centred.

@Esanders and do you agree on that current layout having it vertically centered? I think in order to make it clear that it's an obligatory field it should be vertically-aligned on top, aligning with first line.

Yeah - align top sounds good. There is also an scroll overlap issue with labels:

We'll probably have to calculate the scrollbar width, which is OS dependent: http://stackoverflow.com/questions/8079187/how-to-calculate-the-width-of-the-scroll-bar

Change 249381 had a related patch set uploaded (by Esanders):
TextInputWidget: Ensure icon indicator label are top aligned in multiline mode

https://gerrit.wikimedia.org/r/249381

Change 249395 had a related patch set uploaded (by Esanders):
TextInputWidget: Account for scroll bar width when positioning indicators/labels

https://gerrit.wikimedia.org/r/249395

Change 249381 merged by jenkins-bot:
TextInputWidget: Ensure icon indicator label are top aligned in multiline mode

https://gerrit.wikimedia.org/r/249381

Change 249395 merged by jenkins-bot:
TextInputWidget: Account for scroll bar width when positioning indicators/labels

https://gerrit.wikimedia.org/r/249395

Much better!