Sletter ikke ordentligt i EDIT kontrol

Kode 

#include <windows.h>
#include <fstream>
#include <string>
#include <iostream>

// -----------------------------------
// Variables
// -----------------------------------
bool         draw_ed = FALSE;
char         fileName [256];
CHOOSEFONT   cf;
COLORREF     ed_clr;
HDC          edit_device;
HINSTANCE    instance;
HFONT        CN = CreateFont (16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "Courier New");
HMENU        MainMenu, Files, Formatting;
HWND         MainWindow, EditWindow; // Windows
LOGFONT      lf;
MSG          message;
OPENFILENAME of;

void TestFunc () { MessageBox (NULL, "s", "s", MB_OK); };

// -----------------------------------
// Enumerations
// -----------------------------------
enum {
	enum_open = 001,
	enum_save = 002,
	enum_formatting = 003,
	enum_wordwrap = 004,
	menu_edit = 005,
};

// -----------------------------------
// Program functions interface
// -----------------------------------
int ShowMsg (LPSTR txt); // Show simple MessageBox ()
bool ReadFile (const char *aFileName);
LRESULT CALLBACK MsgDispatch (HWND hwnd, unsigned int message, WPARAM wParam, LPARAM lParam);

// -----------------------------------
// Function declarations
// -----------------------------------
int ShowMsg (LPSTR txt)
{
	return ((int)MessageBox (NULL, txt, "Meddelelse", MB_OK));
};

int WINAPI WinMain (HINSTANCE hInstance,
	HINSTANCE,
	LPSTR,
	int)
{
	instance = hInstance;

	// Create the window menus
	// Code must be inserted here due to the Menu name parameter in the CreateWindowEx function
	MainMenu   = CreateMenu ();
	Files      = CreateMenu ();
	Formatting = CreateMenu ();

	// Append menuitems for Files menu
	AppendMenu (Files, MF_STRING, enum_open, "Åben");
	AppendMenu (Files, MF_STRING, enum_save, "Gem");

	// Append menuitems for Formatting menu
	AppendMenu (Formatting, MF_STRING, enum_formatting, "Skrifttype");
	AppendMenu (Formatting, MF_STRING, enum_wordwrap, "Tekstombrydning");

	// Append menuitems for MainMenu menu
	AppendMenu (MainMenu, MF_POPUP, (unsigned int)Files, "&Filer");
	AppendMenu (MainMenu, MF_POPUP, (unsigned int)Formatting, "F&ormater");

	// Register a new class for the window
	WNDCLASSEX cls;
	cls.cbSize = sizeof (WNDCLASSEX);
	cls.cbWndExtra = 0;
	cls.cbClsExtra = 0;
	cls.lpfnWndProc = MsgDispatch;
	cls.lpszMenuName = NULL;
	cls.lpszClassName = "MAINWINDOW";
	cls.hIcon = LoadIcon (NULL, IDI_APPLICATION);
	cls.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
	cls.hCursor = LoadCursor (NULL, IDC_ARROW);
	cls.hbrBackground = (HBRUSH)COLOR_BACKGROUND;
	cls.hInstance = instance;
	cls.style = 0;
	if (!RegisterClassEx (&cls)) {
		ShowMsg ("Registration failed!");
		return 0; // Exit program in case of errors
	};

	// Create and show main window
	MainWindow = CreateWindowEx (
		WS_EX_CLIENTEDGE,
		cls.lpszClassName, // Make sure to use the correct classname for the window
		"Notesblok",
		WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT, // Positions
		CW_USEDEFAULT, CW_USEDEFAULT, // Dimensions
		NULL, MainMenu, instance, NULL
	);
	if (!MainWindow) {
		ShowMsg ("Creation failed!");
		return 0;
	} else ShowWindow (MainWindow, SW_SHOWMAXIMIZED);

	// -----------------------------------
	// Dialog structures
	// -----------------------------------
	// Due to the window handle, our dialog structures must be set here

	// Open filename structure
	of.lStructSize = sizeof (OPENFILENAME);
	of.hwndOwner = MainWindow;
	of.hInstance = instance;
	of.lpstrFilter = "Tekstdokumenter\\0*.txt\\0Alle filer\\0*.*\\0";
	of.lpstrTitle = "Vælg det dokument, du vil åbne :o)";
	of.lpstrFile = fileName;
	of.nMaxFile = sizeof (fileName);
	of.Flags = OFN_FILEMUSTEXIST | OFN_HIDEREADONLY;
	of.lpstrDefExt = "txt";

	// Choose font structure
	cf.lStructSize = sizeof (CHOOSEFONT);
	cf.hwndOwner = MainWindow;
	cf.lpLogFont = &lf;
	cf.iPointSize = 16;
	cf.Flags = CF_BOTH | CF_EFFECTS | CF_INITTOLOGFONTSTRUCT | CF_FORCEFONTEXIST;
	cf.rgbColors = RGB (0, 0, 0);
	cf.hInstance = instance;
	cf.nFontType = REGULAR_FONTTYPE;

	// Translate and handle (dispatch) messages
	// The dispatching function calls the WindowProcedure function to handle the messages
	// Condition is that the messages value must be greater than 0
	// Because errormessages will have the value of -1 which in boolean is true
	while (GetMessage (&message, NULL, 0, 0) > 0)
	{
		TranslateMessage (&message);
		DispatchMessage (&message);
	};

	return message.wParam;
};

// -----------------------------------
// Function to read a given file
// Thanks to Bertel Brander for this piece of code
// -----------------------------------
bool ReadFile (const char *aFileName)
{
   std::ifstream File (aFileName);
   if (!File)
      return false;
   std::string Line, Text;
   while (std::getline (File, Line))
      Text += Line.c_str ();
   SendMessage (EditWindow, WM_SETTEXT, 0, (LPARAM)Text.c_str ());
   return true;
};

// -----------------------------------
// Message dispatcher
// -----------------------------------
LRESULT CALLBACK MsgDispatch (HWND hwnd,
	unsigned int message,
	WPARAM wParam,
	LPARAM lParam)
{
	switch (message)
	{
		case WM_CREATE:
			EditWindow = CreateWindow (
				"edit",
				NULL,
				WS_CHILD | WS_VISIBLE | ES_MULTILINE | WS_HSCROLL | WS_VSCROLL | ES_NOHIDESEL,
				0, 0, 0, 0, // No dimensions needed; window will be maximized
				hwnd, (HMENU)menu_edit, NULL, NULL
			);
			SendMessage (EditWindow, WM_SETFONT, (WPARAM)CN, NULL);
			SendMessage (EditWindow, EM_SETMARGINS, EC_LEFTMARGIN | EC_RIGHTMARGIN, 2);
			SetFocus (EditWindow);
			break;
		case WM_COMMAND:
			switch (LOWORD (wParam)) {
				case enum_open:
					of.lpstrTitle = "Vælg det dokument, du vil åbne :o)";
					if (GetOpenFileName (&of))
						ReadFile (of.lpstrFile);
					break;
				case enum_save:
					of.lpstrTitle = "Vælg hvor l*rtet skal gemmes";
					if (GetSaveFileName (&of)) {
						std::ofstream saveConn (of.lpstrFile);
						int txtLen = SendMessage (EditWindow, WM_GETTEXTLENGTH, NULL, NULL);
						saveConn << SendMessage (EditWindow, WM_GETTEXT, txtLen, txtLen);
					};
					break;
				case enum_formatting:
					if (ChooseFont (&cf)) {
						// Create and apply new font
						HFONT cfFont = CreateFont (
							lf.lfHeight,
							lf.lfWidth,
							lf.lfEscapement,
							lf.lfOrientation,
							lf.lfWeight,
							lf.lfItalic,
							lf.lfUnderline,
							lf.lfStrikeOut,
							lf.lfCharSet,
							lf.lfOutPrecision,
							lf.lfClipPrecision,
							lf.lfQuality,
							lf.lfPitchAndFamily,
							lf.lfFaceName
						);
						SendMessage (EditWindow, WM_SETFONT, (WPARAM)cfFont, TRUE); // Redraw immediately (TRUE)

						// Create and apply new color
						draw_ed = TRUE;
						ed_clr  = cf.rgbColors;
						SendMessage (MainWindow, WM_CTLCOLOREDIT, (WPARAM)edit_device, TRUE);
					};
					break;
			};
			break;
		case WM_SIZE:
			MoveWindow (EditWindow, 0, 0, LOWORD (lParam), HIWORD (lParam), TRUE);
			break;
		case WM_SETFOCUS:
			SetFocus (EditWindow);
			break;
		case WM_CTLCOLOREDIT:
			if (draw_ed) {
				edit_device = (HDC)wParam;
				SetTextColor (edit_device, ed_clr);
			};
			HDC device_bk = (HDC)wParam;
			SetBkMode (device_bk, TRANSPARENT);
			return ((LRESULT)CreateSolidBrush (RGB (255, 255, 255)));
			break;
		case WM_DESTROY:
			PostQuitMessage (0); // Send WM_QUIT to the queue
			break;
		default:
			return DefWindowProc (hwnd, message, wParam, lParam);
	};
};