Looks like I found the problem.  I was calling SetSize for each item in my OnSize handler, but I wasn't checking first if that particular group was expanded.  So basically, I was resizing an item to nothing because the group height is zero when collapsed.  Thus, the next time I would expand a group the item wouldn't appear.

 

Now I don't resize until I receive a XTP_TPN_GROUPEXPANDED actions from XTPWM_TASKPANEL_NOTIFY.

 

I am trying to use TaskPanel with Version 9.70.  I have created two groups and I use AddControlItem to add a child window to each group.  (One group has a list box, the other group has a tree control.)  I am currently using xtpTaskPanelThemeListViewOffice2003 for my theme, so I can have an Outlook 2003 look.

 

The problem I am having is that switching between groups doesn't make my child windows visible.  For example, if I have Group 1 expanded and am looking at my tree control, then I click to expand Group 2, I don't see my list box.  But I click back onto Group 1, I still see my tree control.  However, after expanding Group 2, if I resize the window, the list box will then reappear.  But then I click back to expand Group 1, and my tree control isn't visible. 

 

It's as if only one CXTPTaskPanelGroupItem can be visible at a time, regardless of whether they are in seperate groups.

 

If anybody can help me, you have my thanks.

 

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BTW, here is my code for creating the Task Panel and contents, if this is any help....

 

 

 if (m_TaskPanel.Create(WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN , CXTPEmptyRect(),  this, IDC_TASKPANEL))
 {
      m_TaskPanel.SetTheme(xtpTaskPanelThemeListViewOffice2003); 
      m_TaskPanel.SetBehaviour(xtpTaskPanelBehaviourToolbox);
      m_TaskPanel.SetSelectItemOnFocus(TRUE);

      m_pItemLayoutGroup = m_TaskPanel.AddGroup(IDS_WORKSPACE_ITEMLAYOUT);
      m_pReportViewGroup = m_TaskPanel.AddGroup(IDS_WORKSPACE_REPORTVIEW);
      m_pReportViewGroup->SetExpanded(TRUE);

      m_treeItemLayout.Create(WS_CHILD | WS_VISIBLE | TVS_HASBUTTONS | TVS_HASLINES | TVS_LINESATROOT | TVS_INFOTIP | TVS_SHOWSELALWAYS, CXTPEmptyRect(), &m_TaskPanel, IDC_WORKSPACE_TREE_SECTIONS);
      m_pItemLayoutItem = m_pItemLayoutGroup->AddControlItem(m_treeItemLayout.GetSafeHwnd());
      m_lstReportSections.Create(WS_CHILD | WS_VISIBLE | LBS_STANDARD | WS_HSCROLL, CXTPEmptyRect(), &m_TaskPanel, IDC_WORKSPACE_LIST_REPORT);
      m_pReportViewItem = m_pReportViewGroup->AddControlItem(m_lstReportSections.GetSafeHwnd());

}