diff --git a/components/nicesidebar/source/NiceSideBar.pas b/components/nicesidebar/source/NiceSideBar.pas
index bdf7fad27..ef9069663 100644
--- a/components/nicesidebar/source/NiceSideBar.pas
+++ b/components/nicesidebar/source/NiceSideBar.pas
@@ -38,7 +38,12 @@ unit NiceSideBar;
 interface
 
 uses
-  Windows, Messages, Graphics, SysUtils, Controls, Classes, ImgList, Math, 
+  {$IFDEF FPC}
+  LCLIntf, LCLType, LMessages,
+  {$ELSE}
+  Windows, Messages,
+  {$ENDIF}
+  Graphics, SysUtils, Controls, Classes, ImgList, Math,
   ExtCtrls, Forms;
 
 const
@@ -265,11 +270,21 @@ type
     FSubItemStyle: TSideBarItemStyle;
     FBullets: TSideBarBulletStyle;
     FScrollers: TSideBarScrollerStyle;
+    {$IFDEF FPC}
+    procedure CMColorChanged(var Msg: TLMessage); message CM_COLORCHANGED;
+    procedure CMMouseLeave(var Msg: TLMessage); message CM_MOUSELEAVE;
+    procedure CMWantSpecialKey(var Message: TLMKey); message CM_WANTSPECIALKEY;
+    procedure WMEraseBkgnd(var Msg: TLMessage); message LM_ERASEBKGND;
+    procedure WMSize(var Msg: TLMSize); message LM_SIZE;
+    procedure WMMouseWheel(var Msg: TLMMouseEvent); message LM_MOUSEWHEEL;
+    {$ELSE}
     procedure CMColorChanged(var Msg: TMessage); message CM_COLORCHANGED;
     procedure CMMouseLeave(var Msg: TMessage); message CM_MOUSELEAVE;
+    procedure CMWantSpecialKey(var Message: TWMKey); message CM_WANTSPECIALKEY;
     procedure WMEraseBkgnd(var Msg: TMessage); message WM_ERASEBKGND;
     procedure WMSize(var Msg: TWMSize); message WM_SIZE;
     procedure WMMouseWheel(var Msg: TWMMouseWheel); message WM_MOUSEWHEEL;
+    {$ENDIF}
     procedure SetItems(Value: TSideBarItems);
     procedure SetItemIndex(Value: Integer);
     procedure SetSubItemIndex(Value: Integer);
@@ -296,7 +311,6 @@ type
     procedure SetSubItemStyle(const Value: TSideBarItemStyle);
     procedure SetBullets(const Value: TSideBarBulletStyle);
     procedure SetScrollers(const Value: TSideBarScrollerStyle);
-    procedure CMWantSpecialKey(var Message: TWMKey); message CM_WANTSPECIALKEY;
   protected
     procedure Notification(AComponent: TComponent; Operation: TOperation); override;
     procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Integer); override;
@@ -697,7 +711,11 @@ var
 
 begin
 
+  {$IFDEF FPC}
+  LCLIntf.SetFocus(Handle);
+  {$ELSE}
   Windows.SetFocus(Handle);
+  {$ENDIF}
 
   if ScTopVisible then
   begin
@@ -875,7 +893,7 @@ begin
 
 end;
 
-procedure TNiceSideBar.CMMouseLeave(var Msg: TMessage);
+procedure TNiceSideBar.CMMouseLeave(var Msg: {$IFDEF FPC}TLMessage{$ELSE}TMessage{$ENDIF});
 begin
   if (HoverIndex <> -1) then
   begin
@@ -1427,19 +1445,19 @@ begin
   end;
 end;
 
-procedure TNiceSideBar.WMEraseBkgnd(var Msg: TMessage);
+procedure TNiceSideBar.WMEraseBkgnd(var Msg: {$IFDEF FPC}TLMessage{$ELSE}TMessage{$ENDIF});
 begin
   Msg.Result := 1;
 end;
 
-procedure TNiceSideBar.WMSize(var Msg: TWMSize);
+procedure TNiceSideBar.WMSize(var Msg: {$IFDEF FPC}TLMSize{$ELSE}TWMSize{$ENDIF});
 begin
   TopIndex := 0;
   ListChange(False);
   Invalidate;
 end;
 
-procedure TNiceSidebar.CMColorChanged(var Msg: TMessage);
+procedure TNiceSidebar.CMColorChanged(var Msg: {$IFDEF FPC}TLMessage{$ELSE}TMessage{$ENDIF});
 begin
   Invalidate;
 end;
@@ -1757,7 +1775,7 @@ begin
   FScrollers := Value;
 end;
 
-procedure TNiceSideBar.WMMouseWheel(var Msg: TWMMouseWheel);
+procedure TNiceSideBar.WMMouseWheel(var Msg: {$IFDEF FPC}TLMMouseEvent{$ELSE}TWMMouseWheel{$ENDIF});
 begin
   if (Msg.WheelDelta > 0) and ScTopVisible then
   begin
@@ -1775,7 +1793,7 @@ begin
     inherited;
 end;
 
-procedure TNiceSideBar.CMWantSpecialKey(var Message: TWMKey);
+procedure TNiceSideBar.CMWantSpecialKey(var Message: {$IFDEF FPC}TLMKey{$ELSE}TWMKey{$ENDIF});
 begin
   inherited;
   with Message do