Delphi 2007 helper class can't access private method - delphi

Question

I have an old Delphi VCL project build in Rad Studio 2007. This version contains a bug in the TScreen.FindMonitor method. I am trying to fix this using a seperate helper class like stated in Is there a runtime patch for AV in TMonitor.GetBoundsRect?.
The only problem is that I can't get this to work. Delphi can't compile and gives error "Cannot access private symbol TScreen.FindMonitor".
Also tried using a WITH self DO statement, casting self to TScreen, casting to pointer and using MethodAddress, but nothing seems to work.
My code
unit PatchTScreen;
interface
implementation
uses
Types, MultiMon, Windows, Forms;
type
TFindMonitorMethod = function(Handle: HMONITOR): TMonitor of object;
TScreenHelper = class helper for TScreen
private
function FindMonitorAddress: Pointer;
function PatchedFindMonitorAddress: Pointer;
function PatchedFindMonitor(Handle: HMONITOR): TMonitor;
end;
function TScreenHelper.FindMonitorAddress: Pointer;
var
MethodPtr: TFindMonitorMethod;
begin
MethodPtr := Self.FindMonitor;
Result := TMethod(MethodPtr).Code;
end;
function TScreenHelper.PatchedFindMonitorAddress: Pointer;
var
MethodPtr: TFindMonitorMethod;
begin
MethodPtr := Self.PatchedFindMonitor;
Result := TMethod(MethodPtr).Code;
end;
function TScreenHelper.PatchedFindMonitor(Handle: HMONITOR): TMonitor;
function DoFindMonitor: TMonitor;
var
I: Integer;
begin
Result := nil;
for I := 0 to MonitorCount - 1 do
if Monitors[I].Handle = Handle then
begin
Result := Monitors[I];
Break;
end;
end;
begin
Result := DoFindMonitor;
if Result = nil then
begin
// If we didn't find the monitor, rebuild the list (it may have changeed)
Self.GetMonitors;
Result := DoFindMonitor;
end;
end;
procedure PatchCode(Address: Pointer; const NewCode; Size: Integer);
var
OldProtect: DWORD;
begin
if VirtualProtect(Address, Size, PAGE_EXECUTE_READWRITE, OldProtect) then
begin
Move(NewCode, Address^, Size);
FlushInstructionCache(GetCurrentProcess, Address, Size);
VirtualProtect(Address, Size, OldProtect, #OldProtect);
end;
end;
type
PInstruction = ^TInstruction;
TInstruction = packed record
Opcode: Byte;
Offset: Integer;
end;
procedure RedirectProcedure(OldAddress, NewAddress: Pointer);
var
NewCode: TInstruction;
begin
NewCode.Opcode := $E9;//jump relative
NewCode.Offset := NativeInt(NewAddress)-NativeInt(OldAddress)-SizeOf(NewCode);
PatchCode(OldAddress, NewCode, SizeOf(NewCode));
end;
initialization
RedirectProcedure(
TScreen(nil).FindMonitorAddress, // safe to use nil, don't need to instantiate an object
TScreen(nil).PatchedFindMonitorAddress // likewise
);
end.
The compile error occures in TScreenHelper.FindMonitorAddress.
The only way I have been able to fix this issue is by changing the original Delphi code of TScreen.FindMonitor in Forms.pas and recomipling the unit with my project. But this is not an actual solution I would like to use, because other developers must make the same changes etc.