Spinner: Ignore mousewheel events when not focused

Fixes #15139 Closes jquerygh-1794

Author: scottgonzalez

tests/unit/spinner/core.js

@@ -162,23 +162,39 @@ QUnit.test( "mouse click on up button, increases value not greater than max", fu
 } );
 
 QUnit.test( "mousewheel on input", function( assert ) {
-assert.expect( 4 );
+var ready = assert.async();
+assert.expect( 5 );
 
 var element = $( "#spin" ).val( 0 ).spinner( {
 step: 2
 } );
 
-element.trigger( "mousewheel" );
-assert.equal( element.val(), 0, "mousewheel event without delta does not change value" );
+element.simulate( "focus" );
+setTimeout( step1 );
 
-element.trigger( "mousewheel", 1 );
-assert.equal( element.val(), 2 );
+function step1() {
+element.trigger( "mousewheel" );
+assert.equal( element.val(), 0, "mousewheel event without delta does not change value" );
 
-element.trigger( "mousewheel", -0.2 );
-assert.equal( element.val(), 0 );
+element.trigger( "mousewheel", 1 );
+assert.equal( element.val(), 2, "delta 1" );
+
+element.trigger( "mousewheel", -0.2 );
+assert.equal( element.val(), 0, "delta -0.2" );
+
+element.trigger( "mousewheel", -15 );
+assert.equal( element.val(), -2, "delta -15" );
 
-element.trigger( "mousewheel", -15 );
-assert.equal( element.val(), -2 );
+element.simulate( "blur" );
+setTimeout( step2 );
+}
+
+function step2() {
+element.trigger( "mousewheel", 1 );
+assert.equal( element.val(), -2, "mousewheel when not focused" );
+
+ready();
+}
 } );
 
 QUnit.test( "reading HTML5 attributes", function( assert ) {

ui/widgets/spinner.js

@@ -140,9 +140,13 @@ $.widget( "ui.spinner", {
 }
 },
 mousewheel: function( event, delta ) {
-if ( !delta ) {
+var activeElement = $.ui.safeActiveElement( this.document[ 0 ] );
+var isActive = this.element[ 0 ] === activeElement;
+
+if ( !isActive || !delta ) {
 return;
 }
+
 if ( !this.spinning && !this._start( event ) ) {
 return false;
 }