From 8e7a33a86344a91b6ca024b4c6899ff71d952ffc Mon Sep 17 00:00:00 2001
From: juha <juha@lazarus-ide.org>
Date: Sat, 14 Apr 2012 20:00:50 +0000
Subject: [PATCH] LazControls: fix potential crash in TListFilterEdit and
 TTreeFilterEdit, issue #21756, patch from Denis

git-svn-id: trunk@36778 -
---
 components/lazcontrols/listfilteredit.pas | 4 ++++
 components/lazcontrols/treefilteredit.pas | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/components/lazcontrols/listfilteredit.pas b/components/lazcontrols/listfilteredit.pas
index a044565876..e35e5ce5cf 100644
--- a/components/lazcontrols/listfilteredit.pas
+++ b/components/lazcontrols/listfilteredit.pas
@@ -173,6 +173,8 @@ var
   s: string;
   clb: TCustomCheckListBox;
 begin
+  if fFilteredListbox = nil then
+    exit;
   clb:=Nil;
   if fFilteredListbox is TCustomCheckListBox then
     clb:=TCustomCheckListBox(fFilteredListbox);
@@ -197,6 +199,8 @@ procedure TListFilterEdit.StoreSelection;
 var
   i: Integer;
 begin
+  if fFilteredListbox = nil then
+    exit;
   fSelectionList.Clear;
   if fFilteredListbox.SelCount > 0 then
     for i := 0 to fFilteredListbox.Count-1 do
diff --git a/components/lazcontrols/treefilteredit.pas b/components/lazcontrols/treefilteredit.pas
index 7f0d55bb8d..caf0f6a62c 100644
--- a/components/lazcontrols/treefilteredit.pas
+++ b/components/lazcontrols/treefilteredit.pas
@@ -438,8 +438,10 @@ procedure TTreeFilterEdit.ApplyFilterCore;
 var
   i: Integer;
 begin
+  if fFilteredTreeview = nil then
+    exit;
   fFilteredTreeview.BeginUpdate;
-  if Assigned(fBranches) then begin      // Apply filter for the brances
+  if Assigned(fBranches) then begin      // Apply filter for the branches
     for i:=0 to fBranches.Count-1 do
       fBranches[i].ApplyFilter;
   end
@@ -459,6 +461,8 @@ var
   ANode: TTreeNode;
 begin
   fSelectionList.Clear;
+  if fFilteredTreeview = nil then
+    exit;
   ANode:=fFilteredTreeview.Selected;
   while ANode<>nil do begin
     fSelectionList.Insert(0,ANode.Text);