tdf#115950: Indicate that the dialog was already destroyed.

The DoubleClickHdl()'s return value does not mean "was handled", but actually
"is there anything more to be done"; so if we actually destroy the dialog in
the aDoubleClickHdl.Call(this), we have to return 'false'.

Change-Id: I7c510e8341eb5f74703b4266f86cb1e840a2b1fd
Reviewed-on: https://gerrit.libreoffice.org/50261
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>
diff --git a/svtools/source/contnr/treelistbox.cxx b/svtools/source/contnr/treelistbox.cxx
index 8bfda5c..ace5eb8 100644
--- a/svtools/source/contnr/treelistbox.cxx
+++ b/svtools/source/contnr/treelistbox.cxx
@@ -428,7 +428,7 @@ void SvTreeListBox::DeselectHdl()
bool SvTreeListBox::DoubleClickHdl()
{
    aDoubleClickHdl.Call( this );
    return true;
    return false;
}