     x = Math.round x
     y = Math.round y
 
+    currentMark = @state.selectedMark
+
     # enforce bounds
     if y < 0
       y = 0 
       return
 
-    currentMark = @state.selectedMark
+    if currentMark.yLower - y < 50      
+      currentMark.yUpper = -50 + currentMark.yLower 
+      @setState selectedMark: currentMark
+      return
 
     dy = currentMark.yUpper - y
     yUpper_p = y

    console.log 'handleLowerResize()'
    {x,y} = @getEventOffset e

    # console.log 'y: ', y

    x = Math.round x
    y = Math.round y

    currentMark = @state.selectedMark

    # console.log 'mark height: ', currentMark.markHeight
    
    # enforce bounds
    if y > @state.imageHeight

      return

    if y - currentMark.yUpper < 50
      currentMark.yLower = 50 + currentMark.yUpper
      @setState selectedMark: currentMark
      return
      
