[MMC] Implement standard "About" menu action (#4639)

Reviewed-by: Serge Gautherie <reactos-git_serge_171003@gautherie.fr>
Reviewed-by: Mark Jansen <mark.jansen@reactos.org>
Reviewed-by: Stanislav Motylkov <x86corez@gmail.com>

base/applications/mmc/console.c

@@ -18,6 +18,7 @@
  */
 
 #include "precomp.h"
+#include <shellapi.h>
 #include <stdlib.h>
 #include <strsafe.h>
 
@@ -311,6 +312,7 @@ FrameOnCommand(HWND hwnd,
 {
     PCONSOLE_MAINFRAME_WND Info;
     HWND hChild;
+    LPTSTR lpTitle;
 
     Info = (PCONSOLE_MAINFRAME_WND)GetWindowLongPtr(hwnd, 0);
 
@@ -334,6 +336,15 @@ FrameOnCommand(HWND hwnd,
             PostMessage(hwnd, WM_CLOSE, 0, 0);
             break;
 
+        case IDM_HELP_ABOUT:
+            if (AllocAndLoadString(&lpTitle, hAppInstance, IDS_APPTITLE))
+            {
+                ShellAbout(hwnd, lpTitle, NULL,
+                           LoadIcon(hAppInstance, MAKEINTRESOURCE(IDI_MAINAPP)));
+                LocalFree(lpTitle);
+            }
+            break;
+
         default:
             if (LOWORD(wParam) >= IDM_MDI_FIRSTCHILD)
             {

base/applications/mmc/misc.c

@@ -55,8 +55,7 @@ LengthOfStrResource(IN HINSTANCE hInst,
     return -1;
 }
 
-
+INT
-static INT
 AllocAndLoadString(OUT LPTSTR *lpTarget,
                    IN HINSTANCE hInst,
                    IN UINT uID)

base/applications/mmc/precomp.h

@@ -32,6 +32,11 @@ INT
 LengthOfStrResource(IN HINSTANCE hInst,
                     IN UINT uID);
 
+INT
+AllocAndLoadString(OUT LPTSTR *lpTarget,
+                   IN HINSTANCE hInst,
+                   IN UINT uID);
+
 DWORD
 LoadAndFormatString(IN HINSTANCE hInstance,
                     IN UINT uID,