Thanks for the report.

Able to reproduce the issue on Win 7, Mac OS X 10.11.4, Ubuntu 14.04 using Chrome Canary #56.0.2907.0, Stable 54.0.2840.87 versions.

This is non-regression issue, issue existing from M40 build, #40.0.2172.0.

Observed errors while running the below URL in Chrome -35.0.1849.0 build.

http://www.bryntum.com/temp/clicktest/

Please find the attached screenshot for reference.

Deleted: 661772-M40.mp4 1.9 MB

	661772-M40.mp4 1.9 MB View Download

Navid, mind taking a look?

mats@ do you have a standalone page that shows the problem? In your example this is the standalone page:
http://www.bryntum.com/temp/clicktest/app.html

and when I try to click the dropdown and choose one of the options no extra scrolling happens anyway.

It's for synthetic events fired, not for manual clicks.

Do you know how that generates those synthetic events? Webdriver or something else? Or is it just "new MouseEvent('type')' and dispatchEvent to the nodes? Because I tried that and that also didn't work.

Yes our testing tool (Siesta) generates these events, createMouseEvent method looks like:

createMouseEvent: function (type, options, el) {
            var event;
            var global      = this.global

            options         = $.extend({
                bubbles     : !/(ms)?(mouse|pointer)enter/i.test(type) && !/(ms)?(mouse|pointer)leave/i.test(type),
                cancelable  : !/(ms)?(mouse|pointer)move/i.test(type),
                view        : global,
                detail      : 0,

                screenX     : 0,
                screenY     : 0,

                ctrlKey     : false,
                altKey      : false,
                shiftKey    : false,
                metaKey     : false,

                /*
                * https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
                *
                * A number representing a given button:

                 0: Main button pressed, usually the left button or the un-initialized state
                 1: Auxiliary button pressed, usually the wheel button or the middle button (if present)
                 2: Secondary button pressed, usually the right button
                 3: Fourth button, typically the Browser Back button
                 4: Fifth button, typically the Browser Forward button

                * */
                button          : 0,
                /*
                * https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/buttons
                *
                * 0  : No button or un-initialized
                * 1  : Left button
                * 2  : Right button
                * 4  : Wheel button or middle button
                * 8  : 4th button (typically the "Browser Back" button)
                * 16 : 5th button (typically the "Browser Forward" button)
                *
                * */
                buttons         : 0,
                relatedTarget   : undefined

            }, options);

            if (!("clientX" in options) || !("clientY" in options)) {
                var center  = this.findCenter(el);

                options     = $.extend({
                    clientX: center[0],
                    clientY: center[1]
                }, options);
            }

            // Not supported in IE
            if ("screenX" in window) {
                options = $.extend(options, {
                    screenX: global.screenX + options.clientX,
                    screenY: global.screenY + options.clientY
                });
            }

            var doc         = el.ownerDocument;

            if (!$.browser.msie && !this.harness.isPhantomJS && global.MouseEvent) {
                event           = new global.MouseEvent(type, options);
            }
            // use W3C standard when available and allowed by "simulateEventsWith" option
            else if (doc.createEvent && this.getSimulateEventsWith() == 'dispatchEvent') {
                var isPointer   = type.match(/^(ms)?pointer/i)

                event           = doc.createEvent(isPointer ? (isPointer[ 1 ] ? 'MS' : '') + 'PointerEvent' : 'MouseEvents');

                event[ isPointer ? 'initPointerEvent' : 'initMouseEvent' ](
                    type, options.bubbles, options.cancelable, options.view, options.detail,
                    options.screenX, options.screenY, options.clientX, options.clientY,
                    options.ctrlKey, options.altKey, options.shiftKey, options.metaKey,
                    options.button, options.relatedTarget || doc.documentElement,
                    // the following extra args are used in the "initPointerEvent"
                    // offsetX, offsetY
                    null, null,
                    // width, height
                    null, null,
                    // pressure, rotation
                    null, null,
                    // tiltX, tiltY
                    null, null,
                    // pointerId
                    null,
                    // pointerType
                    // NOTE: this has to be set to "mouse" (IE11) or 4 (IE10, 11) because otherwise
                    // ExtJS5 blocks the event
                    // need to investigate what happens in SenchaTouch
                    4,//'mouse',
                    // timestamp
                    null,
                    // isPrimary
                    null
                );


            } else if (doc.createEventObject) {
                event       = doc.createEventObject();

                $.extend(event, options);

                event.button = { 0: 1, 1: 4, 2: 2 }[ event.button ] || event.button;
            }

            // Mouse over is used in some certain edge cases which interfer with this tracking
            if (type !== 'mouseover' && type !== 'mouseout') {
                var elWindow    = doc.defaultView || doc.parentWindow;
                var cursorX     = options.clientX;
                var cursorY     = options.clientY;

                // Potentially we're interacting with an element inside a nested frame, which means the coordinates are local to that frame
                if (elWindow !== global) {
                    var offsets = this.$(elWindow.frameElement).offset();

                    cursorX     += offsets.left;
                    cursorY     += offsets.top;
                }

                if (!options.doNotUpdateCurrentPosition) {
                    this.currentPosition[ 0 ]   = cursorX;
                    this.currentPosition[ 1 ]   = cursorY;
                }
            }

            return event;
        },

Were you able to reproduce it?