Steps to Reproduce Case 1

1. visit http://www.zkoss.org/zkdemo/layout/splitter

       <panel title="Splitter" border="normal" width="500px" >
           <panelchildren>
               <hbox spacing="0" width="100%" height="100%">
                   <vbox spacing="0" width="100%"  heights="130px,130px">
                       Column 1-1: The left-top box. To know whether a splitter
                       is collapsed, you can listen to the onOpen event.
                       <splitter id="s1" collapse="before"/>
                       Column 1-2: You can enforce to open or collapse programming
                       by calling setOpen method.
                   </vbox>
                   <splitter id="s2" collapse="before"/>
                   Column 2: Whether a splitter allows users to open or collapse
                   depending on the collapse attribute.
               </hbox>
           </panelchildren>
       </panel>
   

   Paste the code here in case the demo code is changed in the future.

2. follow steps in attached video, splitterPositionSizeIssue.swf
   In video, I move horizontal splitter to rightmost end then leftmost end several times

Actual Result

the horizontal splitter doesn't move to the position I drag to except the first time.

Steps to Reproduce Case 2: Drag to right move to left

1. visit http://www.zkoss.org/zkdemo/layout/splitter
2. follow steps in attached video, drag2RightMove2Left.swf
   1. Drag the horizontal splitter to leftmost end first
   2. drag it to right in a short distance (not to rightmost end)

Actual Result

The horizontal splitter move to the left when I drag it to the right