Installed Themes search: don't blur the search field when pressing Enter

[afercia]

Pressing enter to execute a search is a common pattern. In WordPress all the other pages offer this behaviour. Instead, in themes.php the search field loses focus. Looks like this is intentional:

// Lose input focus when pressing enter
if ( event.which === 13 ) {
	this.$el.trigger( 'blur' );
}

This is confusing especially for keyboard users, not to mention screen reader users are totally lost. In fact, there's a focus loss and users will have to start tabbing again from the beginning of the page.

Would simply propose to remove it, don't see any reason for this feature, unless I'm missing something. See proposed patch.

[joedolson]

Duplicate of #26600.

Duplicate of 26600.