/// <summary>
/// Callback method for the handling of messages to be sent to/from the folder browser dialog.
/// </summary>
/// <param name="hwnd"></param>
/// <param name="msg"></param>
/// <param name="lParam"></param>
/// <param name="lpData"></param>
/// <returns></returns>
private int FolderBrowserDialog_BrowseCallbackProc(IntPtr hwnd, int msg, IntPtr lParam, IntPtr lpData)
{
switch (msg)
{
case NativeWindowCommon.BFFM_INITIALIZED:
// We get in here when the dialog is first displayed. If an initial directory
// has been specified we will make this the selection now, and also make sure
// that directory is expanded.
if (this.selectedPath.Length != 0)
{
NativeWindowCommon.SendMessage(hwnd, NativeWindowCommon.BFFM_SETSELECTIONW, 1, this.selectedPath);
}
break;
case NativeWindowCommon.BFFM_SELCHANGED:
{
IntPtr pidl = lParam;
if (pidl != IntPtr.Zero)
{
StringBuilder sb = new StringBuilder(MAX_PATH * Marshal.SystemDefaultCharSize);
bool flag = NativeWindowCommon.SHGetPathFromIDList(pidl, sb);
NativeWindowCommon.SendMessage(hwnd, NativeWindowCommon.BFFM_ENABLEOK, 0, flag ? 1 : 0);
}
if (!doneScrolling)
{
IntPtr hbrowse = NativeWindowCommon.FindWindowEx(hwnd, IntPtr.Zero, "SHBrowseForFolder ShellNameSpace Control", null);
IntPtr htree = NativeWindowCommon.FindWindowEx(hbrowse, IntPtr.Zero, "SysTreeView32", null);
IntPtr htis = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_CARET, IntPtr.Zero);
IntPtr htir = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_ROOT, IntPtr.Zero);
IntPtr htic = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_CHILD, htir);
//we actually go into the BFFM_SELCHANGED case three times when the dialog is first shown, and it's only on the third one that we actually scroll,
//since before this htic is always zero, so you need to cope with this
//- i.e. don't set 'doneScrolling' flag until htic has been non - zero(or until you've gone into the BFFM_SELCHANGED three times).
if ((int)htic != 0)
{
doneScrolling = true;
//The only solution I've found that works consistently is to send a TVM_ENSUREVISIBLE to the tree, using TVM_GETNEXTITEM/TVGN_CARET, from BFFM_SELCHANGED.
//That works. Every time.
NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_ENSUREVISIBLE, 0, htis);
//Active the tree view control window inside the folder browser dialog to set the focus on it.
NativeWindowCommon.SendMessage(htree, NativeWindowCommon.WM_ACTIVATE, 1, 0);
}
}
}
break;
}
return(0);
}