Scroll language settings on all changes

Change-Id: I550f309d713cb6aac6b18b326379b879dc0b9589

resources/js/ext.uls.displaysettings.js

@@ -532,7 +532,14 @@
 			} );
 
 			$tabButtons.on( 'click', function () {
-				var $button = $( this );
+				var scrollPosition,
+					panelHeight, panelTop, panelBottom,
+					padding,
+					$window,
+					windowHeight,
+					windowScrollTop,
+					windowBottom,
+					$button = $( this );
 
 				if ( $button.hasClass( 'down' ) ) {
 					return;
@@ -550,6 +557,33 @@
 
 				$tabButtons.filter( '.down' ).removeClass( 'down');
 				$button.addClass( 'down' );
+
+				padding = 10;
+				$window = $( window );
+				windowHeight = $window.height();
+				windowScrollTop = $window.scrollTop();
+				windowBottom = windowScrollTop + windowHeight;
+
+				panelHeight = displaySettings.$parent.$window.height();
+				panelTop = displaySettings.$parent.$window.offset().top;
+				panelBottom = panelTop + panelHeight;
+
+				// If the ULS panel is out of the viewport,
+				// scroll the window to show it
+				if ( ( panelTop < windowScrollTop ) || ( panelBottom > windowBottom ) ) {
+					if ( panelHeight > windowHeight ) {
+						// Scroll to show as much of the upper
+						// part of ULS as possible
+						scrollPosition = panelTop - padding;
+					} else {
+						// Scroll just enough to show the ULS panel
+						scrollPosition = panelBottom - windowHeight + padding;
+					}
+
+					$( 'html, body' ).stop().animate( {
+						scrollTop: scrollPosition
+					}, 500 );
+				}
 			} );
 		},