Steps to reproduce

1. load the zul
2. enlarge the width of 4th column of 1st grid
3. click "toggle" button to hide 4th column and show 5th column

result

5th column is still invisible and cannot be switched to be visible

debug information

1. if upi click the toggle button twice at first, the issue never happens.
2. when the issue happens, the hdfaker's width is incorrect, <col id="z_9-hdfaker" style="width: 0.1px;">

   <colgroup id="z_4-hdfaker">
       <col id="z_5-hdfaker" style="width: 267px;">
       <col id="z_6-hdfaker" style="width: 401px;">
       <col id="z_7-hdfaker" style="width: 537px;">
       <col id="z_8-hdfaker" style="width: 0.1px; visibility: hidden;">
       <col id="z_9-hdfaker" style="width: 0.1px;">
       <col id="z_4-hdfaker-bar" style="width: 0.1px;">
   </colgroup>
   

3. In MVC approach, the issue also happens. Refer to 2949-mvc.zul

workaround

http://zkfiddle.org/sample/2srn0ki/2-column-size-workaround