winedbg: Check for visible window station before displaying crash dialog.

programs/winedbg/crashdlg.c

@@ -48,6 +48,20 @@ int msgbox_res_id(HWND hwnd, UINT textid, UINT captionid, UINT type)
     return IDCANCEL;
 }
 
+static BOOL is_visible(void)
+{
+    USEROBJECTFLAGS flags;
+    HWINSTA winstation;
+
+    if (!(winstation = GetProcessWindowStation()))
+        return FALSE;
+
+    if (!(GetUserObjectInformationA(winstation, UOI_FLAGS, &flags, sizeof(flags), NULL)))
+        return FALSE;
+
+    return flags.dwFlags & WSF_VISIBLE;
+}
+
 static WCHAR *get_program_name(HANDLE hProcess)
 {
     WCHAR image_name[MAX_PATH];
@@ -362,7 +376,7 @@ int display_crash_dialog(void)
     /* dbg_curr_process->handle is not set */
     HANDLE hProcess;
 
-    if (!DBG_IVAR(ShowCrashDialog))
+    if (!DBG_IVAR(ShowCrashDialog) || !is_visible())
         return TRUE;
 
     hProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, dbg_curr_pid);