diff --git a/ui (gen4)/data.js b/ui (gen4)/data.js
index ecd21e64..2a019700 100755
--- a/ui (gen4)/data.js	
+++ b/ui (gen4)/data.js	
@@ -935,6 +935,7 @@ module.DataPrototype = {
 	// 		base, should we use last as a base for right shifting???
 	// 		...another way to go could be using current as a reference
 	// XXX test vertical..
+	// XXX should this be called .placeImage(..)???
 	shiftImage: function(from, target, mode){
 		from = from == null ? this.current : from
 		from = from == 'current' ? this.current : from
@@ -1004,17 +1005,31 @@ module.DataPrototype = {
 				order.splice(t+i, 0, this.order.splice(f, 1)[0])
 
 				// update ribbons...
-				for(k in ribbons){
-					var e = ribbons[k].splice(f, 1)[0]
-					ribbons[k].splice(t+i, 0, e)
-					// remove the null/undefined if it was just inserted...
-					// NOTE: this needs to be done as splice inserts the 3'rd
-					// 		argument explicitly regardless of it's value,
-					// 		this if not done we'll end up with undefined 
-					// 		inserted into a sparse ribbon which will be
-					// 		considered as an element...
-					if(e == null){
-						delete ribbons[k][t+i]
+				for(var k in ribbons){
+					var r = ribbons[k]
+
+					var e = r.splice(f, 1)[0]
+
+					// NOTE: for some magical reason L.slice(n, .., x) will
+					// 		append x to L rather than place it at position 
+					// 		n, if L.length < n
+					// 		...this we can't use .splice(..) for cases when 
+					// 		inserting after the last element of the array...
+					if(r.length > t+i){
+						r.splice(t+i, 0, e)
+
+						// remove the null/undefined if it was just inserted...
+						// NOTE: this needs to be done as splice inserts the 3'rd
+						// 		argument explicitly regardless of it's value,
+						// 		this if not done we'll end up with undefined 
+						// 		inserted into a sparse ribbon which will be
+						// 		considered as an element...
+						if(e == null){
+							delete r[t+i]
+						}
+
+					} else if(e != null){
+						r[t+i] = e
 					}
 				}
 			}
diff --git a/ui (gen4)/experiments/scale-origin.html b/ui (gen4)/experiments/scale-origin.html
index 5c0b2457..dfe0cb8c 100755
--- a/ui (gen4)/experiments/scale-origin.html	
+++ b/ui (gen4)/experiments/scale-origin.html	
@@ -81,6 +81,7 @@ function setOffset(l, t){
 
 function setScale(s){
 	setElementScale($('.block'), s)
+	// compensate for point scale...
 	setElementScale($('.point'), 1/s)
 	setElementScale($('.point-old'), 1/s)
 }
@@ -111,6 +112,7 @@ function setOrigin(l, t, no_comp){
 }
 
 
+
 // Center a block to a point...
 //
 // If not coordinates are given then center to element origin...
@@ -121,44 +123,21 @@ function setOrigin(l, t, no_comp){
 //		supported keywords:
 //			'screen'
 //			'elem'
+//
+// XXX need to make this independent of current position...
+//		...this is to prevent it from getting the wrong target coords 
+//		during animations..
 function centerBlock(l, t, scale){
 	var block = $('.block')
-	var s = getElementScale(block)
+	var container = $('.container')
 
-	scale = scale == 'screen' ? 1 
-		: scale == 'elem' ? s
-		: s
+	var offset = getRelativeOffset(container, block, {
+			top: t,
+			left: l,
+			scale: scale,
+		})
 
-	var offset = getElementOffset(block)
-	
-	var bo = block.offset()
-	var co = $('.container').offset()
-
-	var W = $('.container').width()
-	var H = $('.container').height()
-
-	var o = getElementOrigin(block)
-
-	// normalize the l,t to element scale...
-	if(l != null && t != null){
-
-		var w = block.width()
-		var h = block.height()
-		o = {
-			// target offset scale...
-			top: t*scale 
-				// set origin to top left corner of element (compensate
-				// for scaling)...
-				+ (h - h*s) / (w / o.left), 
-			left: l*scale 
-				+ (w - w*s) / (h / o.left),
-		}
-	}
-
-	var dl = offset.left + (W/2 - offset.left) - o.left
-	var dt = offset.top + (H/2 - offset.top) - o.top
-
-	setOffset(dl, dt)
+	setOffset(offset.left, offset.top)
 }
 
 
diff --git a/ui (gen4)/lib/jli.js b/ui (gen4)/lib/jli.js
index 730e65ed..327e4748 100755
--- a/ui (gen4)/lib/jli.js	
+++ b/ui (gen4)/lib/jli.js	
@@ -550,6 +550,73 @@ var getElementTransitionDuration = makeCSSVendorAttrGetter(
 		parseInt)
 
 
+// Get relative offset...
+//
+// This is like jQuery.offset() but takes into account:
+//	- scale
+//	- origin
+//	- actual relative offset
+//
+// point can be:
+//	- {
+//		top: <top>, 
+//		left: <left>,
+//		[scale: 'screen'|'elem'|<scale>,]
+//	  }
+//	- 'origin' (default)
+//
+// This expects: 
+// 	- the block is directly nested in the container
+// 	- the block can be scaled
+// 	- the block has an origin set
+//
+function getRelativeOffset(container, block, point){
+	point = point == null ? {} : point
+	var l = point.left
+	var t = point.top
+	var scale = point.scale
+
+	// get the input data...
+	var s = getElementScale(block)
+	var o = getElementOrigin(block)
+	// get only the value we need...
+	var W = container.width()
+	var H = container.height()
+	// we need this to make everything relative to the container...
+	var co = container.offset()
+	var offset = getElementOffset(block)
+	var bo = block.offset()
+
+	scale = scale == 'screen' ? 1 
+		: scale == 'elem' ? s
+		: scale
+
+	// normalize the l,t to element scale...
+	if(l != null && t != null){
+
+		// get only the value we need...
+		// NOTE: width and height are used to calculate the correction
+		//		due to origin/scale...
+		var w = block.width()
+		var h = block.height()
+		o = {
+			// target offset scale...
+			top: t*scale 
+				// set origin to top left corner of element (compensate
+				// for scaling)...
+				+ (h - h*s) / (h / o.top), 
+			left: l*scale 
+				+ (w - w*s) / (w / o.left),
+		}
+	}
+
+	return {
+		top: offset.top + (H/2 - offset.top) - o.top,
+		left: offset.left + (W/2 - offset.left) - o.left,
+	}
+}
+
+
 // NOTE: at this point this works only on the X axis...
 function setElementTransform(elem, offset, scale, duration){
 	elem = $(elem)
diff --git a/ui (gen4)/ribbons.js b/ui (gen4)/ribbons.js
index 2f270e8d..37ef121d 100755
--- a/ui (gen4)/ribbons.js	
+++ b/ui (gen4)/ribbons.js	
@@ -1488,6 +1488,14 @@ module.RibbonsPrototype = {
 		// 		...it's getting closer when enlarging and blows up when scale -> 0
 		offset -= (ot/scale - ot)
 
+		/*
+		var ribbon_set = this.viewer.find('.ribbon-set')
+		// XXX this needs the correct origin set before centering...
+		// XXX at scale this does not center corretly if ribbon is offset...
+		// 		...calling it multiple times gets it closer and closer...
+		var offset = getRelativeOffset(this.viewer, ribbon_set).top
+		*/
+
 		console.log('### offset-top:', offset)
 
 		setElementOffset(this.viewer.find('.ribbon-set'), 0, offset)
diff --git a/ui (gen4)/viewer.js b/ui (gen4)/viewer.js
index de1597be..9434d959 100755
--- a/ui (gen4)/viewer.js	
+++ b/ui (gen4)/viewer.js	
@@ -403,6 +403,11 @@ actions.Actions(Client, {
 					// XXX is there a 'last' special case here???
 					var t = data.getImage(gid, r)
 					if(t == null){
+						var f = data.getImage('first', r)
+						// nothing found -- empty ribbon?
+						if(f == null){
+							continue
+						}
 						ribbons.centerImage(data.getImage('first', r), 'before')
 					} else {
 						ribbons.centerImage(t, 'after')