steps to reproduce

1. run the zul below

   <tabbox width="400px" height="300px">
       <tabs>
           <tab label="Tab 1" />
           <tab label="Tab 2" />
           <tab label="Tab 3" />
           <tab label="Tab 4" />
           <tab label="Tab 5" />
           <tab label="Tab 6" />
           <tab label="Tab 7" />
           <tab label="Tab 8" />
           <tab label="Tab 9" />
           <tab label="Tab 10" />
       </tabs>
       <tabpanels>
           <tabpanel style="color:#336699;">Panel 1</tabpanel>
           <tabpanel style="color:#333399;">Panel 2</tabpanel>
           <tabpanel style="color:#663366;">Panel 3</tabpanel>
           <tabpanel style="color:#CC0033;">Panel 4</tabpanel>
           <tabpanel style="color:#CC3300;">Panel 5</tabpanel>
           <tabpanel style="color:#FF9900;">Panel 6</tabpanel>
           <tabpanel style="color:#ABEA14;">Panel 7</tabpanel>
           <tabpanel style="color:#008DB7;">Panel 8</tabpanel>
           <tabpanel style="color:#CDCD3E;">Panel 9</tabpanel>
           <tabpanel style="color:#C34576;">Panel 10</tabpanel>
       </tabpanels>
   </tabbox>
   

2. set zoom level other than 100%, e.g. 110%
3. move tabs right

result

Can not show Tab 8 ~ Tab 10

debug information

• HTMLElement.scrollIntoView() doesn't work for Chrome's design: https://bugs.webkit.org/show_bug.cgi?id=42593
  In its comment, it mentions
  // If the rectangle is partially visible, but over a certain threshold,
  // then treat it as fully visible to avoid unnecessary horizontal scrolling

workaround

see attached zul