UPDATED TICKET 

Steps to Reproduce

1. https://zkfiddle.org/sample/2susg7b/1-Firefox-118-focus-scrolls-to-wrong-scroll-postion
2. Run fiddle in FF 118
3. scroll down to the middle of the tree
4. open or close an item

Current Result

Tree scrolls up by half of a tree viewport

Expected Result

tree doesn't scroll

Debug Information

Caused by FF incorrectly scrolling the tree viewport to center the hidden focus button, instead of scrolling the tree viewport to put the hidden focus button tot the top of the viewport.

fiddle sample uses a red border on the hidden focus to make it visible

Triggering the behavior in FF causes the focus called on the button during zul.sel.Tree.prototype.focusA_ to scroll the button to the center of the viewport

triggering the same behavior in other browsers  / versions bring the focus button to the top of the viewport instead.

Workaround

scrolls the viewport back to expect location after triggering button focus.

	<script><![CDATA[
	/*WORKAROUND*/
	/**
		 * Purpose: prevent unwanted scroll in FF
		 * Based on version: 9.6.4
		 * Last update: 9.6.4
	 */
	if(zk.version != '9.6.4'){
	   console.warn('This override script version compatibility was tested for ZK 9.6.4. If you are running a different version, please check this script compatibility ');
	}
	zk.afterLoad("zul.sel", function () {
	    var _xTree = {};
	    zk.override(zul.sel.Tree.prototype, _xTree, {
	        focusA_: function() {
				var result = _xTree.focusA_.apply(this, arguments);
				if(zk.ff)
					this.$n("body").scrollTop = this._currentTop;
				return result;
	        }
	     });
	});
]]></script>

ORIGNAL TICKET BELOW

Steps to Reproduce

Create a tree that will contain enough treeitems to display a vertical scrollbar. Treeitems must have children (so they can be opened/closed). Move the vertical scrollbar down to the item that was not visible. Open an treeitem - the item's position will change and you have to use the scrollbar to find the item. The same happens when closing an item.

Current Result

If the vertical scrollbar of the tree is not at the top, then opening/closing the item will change its position

Expected Result

The treeitem should stay in the same position after opening/closing.

Debug Information

 
I am sending a test index.zul file in the attachment

Workaround

The tree works correctly in an older version of Firefox or in the Chrome browser.