Hi again - thanks again for the fast response on my last request - hoping for another fast one here ;-) So, Cello (the original one) has this function: (defun find-ix-under (self os-pos &key (test #'true)) (when (and (not (typep self 'tool-tip)) ;; <g> (visible self) (not (collapsed self))) (trc nil "find-ix-under" self os-pos (screen-box self)) (let ((inself (point-in-box os-pos (screen-box self)))) (or (when (or inself (not (clipped self))) (trc nil "inside self sbox" self os-pos (screen-box self)) (dolistreversed (k (or (render-order self)(kids self))) ;; overlap goes to last kid displayed (unless (typep k 'window) (trc nil "fixunder kid!!!!!!!!" k) (bwhen (ix (find-ix-under k os-pos :test test)) (return-from find-ix-under ix))))) (when (and inself (funcall test self) (not (ix-click-transparent self))) (trc nil self os-pos (screen-box self)) self))))) which is used as follows: (defmd mouse-view-tracker () (mouse-view :initarg :mouse-view :accessor mouse-view :initform (c? (let ((pos (mouse-pos .og.))) (trc nil "mouseview sees pos" .w. pos) (when pos (eko (nil "ix-togl mouseview >" self) (without-c-dependency (find-ix-under self pos))))))) (:documentation "Mixin to have mouse view tracked in a subtree of the window, mostly so other GUI layout can depend on the sub-tree layout without creating a cyclic dependency, as would happen iof the whole window were watched.")) (defmd ix-togl (mouse-view-tracker #+not focuser ogl-lit-scene control ogl-shared-resource-tender togl ix-view) ... So, the togl widget is a sub-class of mouse-view-tracker. I understand this as "show me the control that is currently being pointed at by the mouse". Only thing is: When looking at the code for 'find-ix-under I can't see how this could possibly work? May I ask for a walk-through of find-ix- under ? Thanks!!! Cheers Frank -- Frank Goenninger Cell: +49 175 4321058 E-Mail: frgo@me.com