Force the display of scroll bars in a ListView?

Question

• The background: Most of us know the SysListView32 common control and the equivalent wrapper ListView class provided by th

Answer 1

• Information:

  • Firstly, I have to admit this is an okay answer and not the best/most efficient one. If you have a different answer from mine, please post it.
  • Secondly, this answer owes some credit to Plutonix's answer, experimenting with which I learned that by default ListView does not have WS_HSCROLL | WS_VSCROLL flags set in its styles.
    • This is why my previous workaround had problem with themes.
    • These Classic scroll bars are ones Windows provides to Controls that do not have these flags set.
    • Changing the CreateParams does not work either. You have to set it manually in the OnHandleCreated method using SetWindowLong.
    • The solution I am posting does not use the above technique. Apparently, calling ShowScrollBar for each window message forces these flags to be set.

• The Solution:

  • Define your WndProc like the following:

    protected override void WndPoc(ref Message m)
    {
    //custom code before calling base.WndProc
    base.WndProc(ref m);
    //custom after base.WndProc returns
    WmScroll(); //VERY INEFFICIENT, called for each message :(
    }
    

  • Define WmScroll() as follows:

    protected virtual void WmScroll()
    {
    NativeMethods.ShowScrollBar(Handle, SB_BOTH, true);
    	
    //si.fMask = SIF_PAGE | SIF_RANGE <- initialized in .ctor
    	
    NativeMethods.GetScrollInfo(Handle, SB_HORZ, ref si);
    if(si.nMax < si.nPage)
    	NativeMethods.EnableScrollBar(Handle, SB_HORZ, ESB_DISABLE_BOTH);
    else
    	NativeMethods.EnableScrollBar(Handle, SB_HORZ, ESB_ENABLE_BOTH);
    NativeMethods.GetScrollInfo(Handle, SB_VERT, ref si);
    if(si.nMax < si.nPage)
    	NativeMethods.EnableScrollBar(Handle, SB_VERT, ESB_DISABLE_BOTH);
    else
    	NativeMethods.EnableScrollBar(Handle, SB_VERT, ESB_ENABLE_BOTH);
    }
    

  • Output:

It now, looks like:

These are with another item added featuring the horizontal scroll and working ListViewGroup collapse button:

• Imperfection, yes there is:
  • A call to AutoResizeColumns is required if group collapse changes effective text width, otherwise the vertical scroll bar hides the collapse buttons.