Invalid access to memory - Vcl::Controls::TWinControl::DefaultHandler

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.5.3

Error message:
Unzulässiger Zugriff auf einen Speicherbereich.

Stapelverfolgung:
(00139AAC)
(00EF5B8E)
(00EF7C06)
(00EF49B0)
(0008818F) ntdll.dll
(00074711) ntdll.dll.KiUserExceptionDispatcher
(00084CA6)
(00084D6D)
(00082F37)
(00D8B9E5)
(00D8B9A2)
(003A3455)
(004A769C)
(00E0573F)
(003A2960)
(00204B78)
(00040489) USER32.dll
(00036B75) USER32.dll
(0003678B) USER32.dll
(0003AC4D) USER32.dll
(000746CB) ntdll.dll.KiUserCallbackDispatcher
(00034BF7) USER32.dll
(000325C3) UXTHEME.DLL
(0002EADF) UXTHEME.DLL
(0002E753) UXTHEME.DLL
(00035845) USER32.dll.GetSystemMetricsForDpi
(00040489) USER32.dll
(00036B75) USER32.dll
(000362A1) USER32.dll.GetSystemMetricsForDpi
(00034AD6) USER32.dll.CallWindowProcW
(003A355D)
(004AB0E5)
(003A3455)
(004A769C)
(00E0565F)
(003A2960)
(00204B78)
(00040489) USER32.dll
(00036B75) USER32.dll
(0003678B) USER32.dll
(0003AC4D) USER32.dll
(000746CB) ntdll.dll.KiUserCallbackDispatcher
(0003ADC9) USER32.dll.PeekMessageW
(004B1958)
(00C9BE01)
(00C98F5B)
(00CF3374)
(00D0A73D)
(00D0AA70)
(00D0A4EE)
(00D3BAD4)
(00D3BCD0)
(000172DB)
(0001EB06)
(0001E966)
(00509A71)
(00507512)
(00508145)
(003A3455)
(0041AF67)
(00204B78)
(00040489) USER32.dll
(00036B75) USER32.dll
(000362A1) USER32.dll.GetSystemMetricsForDpi
(00034AD6) USER32.dll.CallWindowProcW
(0007A1F7) COMCTL32.DLL
(0007A296) COMCTL32.DLL
(0007A04C) COMCTL32.DLL
(00040489) USER32.dll
(00036B75) USER32.dll
(000362A1) USER32.dll.GetSystemMetricsForDpi
(00034AD6) USER32.dll.CallWindowProcW
(0053941F)
(00204B78)
(00040489) USER32.dll
(00036B75) USER32.dll
(0003541B) USER32.dll
(00034F4B) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.5.2

Error message:
Invalid access to memory.

Stack trace:
(0007C998) MSFTEDIT.DLL
(000B0F8F) ntdll.dll
(0007ACDA) ntdll.dll.KiUserExceptionDispatcher
(0007CA2A) MSFTEDIT.DLL
(00202399) MSFTEDIT.DLL.RichEditWndProc
(00038A11) USER32.dll
(00026B88) USER32.dll
(000262F5) USER32.dll.CallWindowProcW
(003A355D) Vcl::Controls::TWinControl::DefaultHandler
(00D869A8) TEditorRichEdit::Dispatch
(003A3455) Vcl::Controls::TWinControl::WndProc
(003A2960) Vcl::Controls::TWinControl::MainWndProc
(00204B78) System::Classes::_18364
(00038A11) USER32.dll
(00026B88) USER32.dll
(0002662B) USER32.dll
(00032EA7) USER32.dll
(0007ACB4) ntdll.dll.KiUserCallbackDispatcher
(0003F3D3) USER32.dll
(00026351) USER32.dll.SendMessageW
(00D869C4) TEditorRichEdit::GetCanRedo
(00221808) System::Actions::TContainedActionList::UpdateAction
(0038AC89) Vcl::Actnlist::TCustomAction::Update
(004ACE0A) Vcl::Forms::_16859
(004ACE7B) Vcl::Forms::TCustomForm::UpdateActions
(004B28D2) Vcl::Forms::TApplication::DoActionIdle
(004B1A87) Vcl::Forms::TApplication::HandleMessage
(0012A131) Execute
(000033BB) wWinMain
(00EF2BF1) C7146_0
(0006C099) ntdll.dll
(0006C01C) ntdll.dll

The problem happens rarely. I cannot reproduce it.

@aditya: Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.