Tree: CSS customization when dropRestrict=sibling is enable

[zakhdar]

Description

When drag&drop is activated on a p:tree with the dropRestrict = sibling attribute, when we click on a node to move it, it would be interesting to change the color of the drop point if it is a valid drop point or not, that would allow for a more intuitive interaction.

Describe the solution you would like
A solution would be to have a attribute like siblingClass when we can define for example the color of drop point if drag&drop is authorized or not

Example when drag&drop is in same parent node

Example when drag&drop is out of parent node

[melloware]

This is pretty tricky since PF doesn't evaluate whether the drop is allowed until AFTER you actually drop the node.

/**
     * After a drag&drop, validates if the drop is allowed.
     * @private
     * @param {JQuery} dragNode Node that was dragged.
     * @param {JQuery} dropPoint Element where the node was dropped.
     * @return {boolean} Whether the drop is allowed.
     */
    validateDropPoint: function(dragNode, dropPoint) {
        //dropped before or after
        if(dragNode.next().get(0) === dropPoint.get(0)||dragNode.prev().get(0) === dropPoint.get(0)) {
            return false;
        }

        //descendant of dropnode
        if(dragNode.has(dropPoint.get(0)).length) {
            return false;
        }

        //drop restriction
        if(this.cfg.dropRestrict) {
            if(this.cfg.dropRestrict === 'sibling' && dragNode.parent().get(0) !== dropPoint.parent().get(0)) {
                return false;
            }
        }

        return true;
    },

So it will be tough to preemptively tell its not allowed to drop and change the helper css to a different style. At least not without some major rework of the tree drag and drop.

[melloware]

Going to mark this as won't fix only because it is not currently possible