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:
Invalid access to memory.

Stack trace:
(0007C9B8) MSFTEDIT.DLL
(000B204F) ntdll.dll
(0007AF3A) ntdll.dll.KiUserExceptionDispatcher
(0007CA4A) MSFTEDIT.DLL
(00202D69) MSFTEDIT.DLL.RichEditWndProc
(00038D01) USER32.dll
(00026E78) USER32.dll
(000265E5) USER32.dll.CallWindowProcW
(003A355D) Vcl::Controls::TWinControl::DefaultHandler
(00D8740C) TEditorRichEdit::Dispatch
(003A3455) Vcl::Controls::TWinControl::WndProc
(003A2960) Vcl::Controls::TWinControl::MainWndProc
(00204B78) System::Classes::_18364
(00038D01) USER32.dll
(00026E78) USER32.dll
(0002691B) USER32.dll
(00033197) USER32.dll
(0007AF14) ntdll.dll.KiUserCallbackDispatcher
(0003F6C3) USER32.dll
(00026641) USER32.dll.SendMessageW
(00D87428) 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
(00EF38D1) C7146_0
(0006C2F9) ntdll.dll
(0006C27C) ntdll.dll

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.

<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.