.NET (Core and Framework)

public partial class Form1 : Form
{
    public Form1() {
        InitializeComponent();
        textBox2.AllowDrop = true;
        Application.ThreadException += OnThreadException;
    }

    void OnThreadException(object sender, ThreadExceptionEventArgs e) {
        MessageBox.Show(e.Exception.Message);
    }

    private void button1_Click(object sender, EventArgs e) {
        throw new ApplicationException("button1_Click");
    }

    private void textBox1_MouseDown(object sender, MouseEventArgs e) {
        DoDragDrop(sender, DragDropEffects.All);
    }

    private void textBox2_DragEnter(object sender, DragEventArgs e) {
        e.Effect = e.AllowedEffect;
    }

    private void textBox2_DragDrop(object sender, DragEventArgs e) {
        MessageBox.Show("I'm here!");
        throw new ApplicationException("You'll never see this :-(");
    }
}

<br />
// MODULE.H<br />
// (c) 2004 - Cyril Hruscak<br />
#ifndef	__FS_MODULE_H__<br />
#define	__FS_MODULE_H__<br />
<br />
#define	DLLEXPORT	__declspec(dllexport)<br />
#define	FSAPI	__stdcall<br />
<br />
/**<br />
 * This is the module's import table definition.<br />
 */<br />
typedef struct _MODULE_IMPORT {<br />
	struct {<br />
		int fnID;<br />
		PVOID fnptr;<br />
	} IMPORTSentry;<br />
	struct {<br />
		int fnID;<br />
		PVOID fnptr;<br />
	} nullentry;<br />
} MODULE_IMPORT;<br />
<br />
/**<br />
 * This is the module's export table definition<br />
 */<br />
typedef struct _MODULE_LINKAGE {<br />
	int ModuleID;<br />
	void (FSAPI *ModuleInit)(void);<br />
	void (FSAPI *ModuleDeinit)(void);<br />
	UINT32 ModuleFlags;<br />
	UINT32 ModulePriority;<br />
	UINT32 ModuleVersion;<br />
	PVOID ModuleTable;<br />
} MODULE_LINKAGE;<br />
<br />
#endif	/* __FS_MODULE_H__ */<br />

<br />
// MAIN.C<br />
// (c) 2004 - Cyril Hruscak<br />
#include <windows.h><br />
#include "module.h"<br />
<br />
/*<br />
 * We define just basic interface to the flight simulator so it will be<br />
 * able to load the module.<br />
 */<br />
DLLEXPORT MODULE_IMPORT ImportTable = {<br />
	{0x00000000, NULL},<br />
	{0x00000000, NULL}<br />
};<br />
<br />
void FSAPI module_init(void) {}<br />
void FSAPI module_deinit(void) {}<br />
<br />
DLLEXPORT MODULE_LINKAGE Linkage = {<br />
	0x00000000,<br />
	module_init,<br />
	module_deinit,<br />
	0,<br />
	0,<br />
	0x0900,	// FS2004 version (use 0x0800 for FS2002)<br />
	NULL<br />
};<br />
<br />
// The standard window procedure used by the flight simulator<br />
WNDPROC oldWndProc;<br />
<br />
// Flight simulator main window handle<br />
HWND hFSimWindow;<br />
<br />
#define	MENU_ENTRY	"My Mo&dule"<br />
#define	ID_MY_MENUITEM	40001<br />
<br />
/**<br />
 * Main window procedure that is called by the flight simulator to process<br />
 * incoming window messages.<br />
 */<br />
LRESULT CALLBACK FSimWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)<br />
{<br />
	switch (uMsg) {<br />
		case WM_NCPAINT:<br />
			{<br />
				HMENU hMenu, hMyMenu;<br />
<br />
				hMenu = GetMenu(hwnd);<br />
				if (hMenu != NULL) {<br />
					int i;<br />
					// Look for our menu entry in the main menu.<br />
					for (i = 0; i < GetMenuItemCount(hMenu); i++) {<br />
						char buf[128];<br />
						GetMenuString(hMenu, i, buf, 128, MF_BYPOSITION);<br />
						if (strcmp(buf, MENU_ENTRY) == 0) {<br />
							// It is already here, we do not need to add it again<br />
							break;<br />
						}<br />
					}<br />
					if (i < GetMenuItemCount(hMenu)) {<br />
						// It is already here, we do not need to add it again<br />
						break;<br />
					}<br />
					/* Create new menu. NOTE: It seems that this will be<br />
					 * reached more times, so we cannot save the handle, because<br />
					 * in such case it could be destroyed and we will not have<br />
					 * any access to it in the simulator.<br />
					 */<br />
					hMyMenu = CreateMenu();<br />
					AppendMenu(hMyMenu, MF_STRING | MF_ENABLED, ID_MY_MENUITEM, "My &First Menu Entry");<br />
					// add the created menu to the main menu<br />
					AppendMenu(hMenu, MF_STRING | MF_POPUP, (UINT_PTR)hMyMenu, MENU_ENTRY);<br />
				}<br />
			}<br />
			break;<br />
		case WM_COMMAND:<br />
			if (LOWORD(wParam) == ID_MY_MENUITEM) {<br />
				// Add your code here<br />
				MessageBox(hwnd, "It works!", "HURA", MB_OK | MB_ICONEXCLAMATION);<br />
				return 0;<br />
			}<br />
			break;<br />
	}<br />
	// Call the original window procedure to handle all other messages<br />
	return CallWindowProc(oldWndProc, hwnd, uMsg, wParam, lParam);<br />
}<br />
<br />
/**<br />
 * Entry point of the DLL.<br />
 */<br />
BOOL WINAPI DllMain(HINSTANCE hInstDLL, DWORD fdwReason, LPVOID lpvReserved)<br />
{<br />
	switch (fdwReason) {<br />
		case DLL_PROCESS_ATTACH:<br />
			hFSimWindow = FindWindow("FS98MAIN", NULL);<br />
			oldWndProc = (WNDPROC)SetWindowLong(hFSimWindow, GWL_WNDPROC, (LONG)FSimWindowProc);<br />
			break;<br />
	}<br />
	return TRUE;<br />
}<br />