Use "Select All" instead of "Mark" to freeze the console.

The Mark command moves the cursor to the top-left, which interferes with
lynx, a full-screen Cygwin web browser, and probably other programs.
The Select All command also puts the console into selection mode, blocking
console output.

Agent/Agent.cc

@@ -13,6 +13,7 @@
 #include <windows.h>
 
 const int SC_CONSOLE_MARK = 0xFFF2;
+const int SC_CONSOLE_SELECT_ALL = 0xFFF5;
 const int SYNC_MARKER_LEN = 16;
 #define CSI "\x1b["
 
@@ -47,7 +48,7 @@ Agent::Agent(const QString &socketServer,
     m_timer = new QTimer(this);
     m_timer->setSingleShot(false);
     connect(m_timer, SIGNAL(timeout()), SLOT(pollTimeout()));
-    m_timer->start(500);
+    m_timer->start(25);
 
     Trace("agent starting...");
 }
@@ -322,7 +323,7 @@ void Agent::scrapeOutput()
 
 void Agent::freezeConsole()
 {
-    SendMessage(m_console->hwnd(), WM_SYSCOMMAND, SC_CONSOLE_MARK, 0);
+    SendMessage(m_console->hwnd(), WM_SYSCOMMAND, SC_CONSOLE_SELECT_ALL, 0);
 }
 
 void Agent::unfreezeConsole()

Misc/SelectAllTest.cc

@@ -0,0 +1,40 @@
+#define _WIN32_WINNT 0x0501
+#include <stdio.h>
+#include <windows.h>
+
+const int SC_CONSOLE_MARK = 0xFFF2;
+const int SC_CONSOLE_SELECT_ALL = 0xFFF5;
+
+CALLBACK DWORD pausingThread(LPVOID dummy)
+{
+  HWND hwnd = GetConsoleWindow();
+  while (true) {
+    SendMessage(hwnd, WM_SYSCOMMAND, SC_CONSOLE_SELECT_ALL, 0);
+    SendMessage(hwnd, WM_CHAR, 27, 0x00010001);
+  }
+}
+
+int main()
+{
+  HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
+  CONSOLE_SCREEN_BUFFER_INFO info;
+
+  GetConsoleScreenBufferInfo(out, &info);
+  COORD initial = info.dwCursorPosition;
+
+  CreateThread(NULL, 0,
+	       pausingThread, NULL,
+	       0, NULL);
+
+  while (true) {
+    GetConsoleScreenBufferInfo(out, &info);
+    if (memcmp(&info.dwCursorPosition, &initial, sizeof(COORD)) != 0) {
+      printf("cursor moved to [%d,%d]\n", 
+	     info.dwCursorPosition.X,
+	     info.dwCursorPosition.Y);
+      GetConsoleScreenBufferInfo(out, &info);
+      initial = info.dwCursorPosition;
+    }
+  }
+  return 0;
+}

Misc/VkEscapeTest.cc

@@ -0,0 +1,56 @@
+/*
+ * Sending VK_PAUSE to the console window almost works as a mechanism for
+ * pausing it, but it doesn't because the console could turn off the
+ * ENABLE_LINE_INPUT console mode flag.
+ */
+
+#define _WIN32_WINNT 0x0501
+#include <stdio.h>
+#include <stdlib.h>
+#include <windows.h>
+
+CALLBACK DWORD pausingThread(LPVOID dummy)
+{
+  if (1) {
+    Sleep(1000);
+    HWND hwnd = GetConsoleWindow();
+    SendMessage(hwnd, WM_KEYDOWN, VK_PAUSE, 1);
+    Sleep(1000);
+    SendMessage(hwnd, WM_KEYDOWN, VK_ESCAPE, 1);
+  }
+
+  if (0) {
+    INPUT_RECORD ir;
+    memset(&ir, 0, sizeof(ir));
+    ir.EventType = KEY_EVENT;
+    ir.Event.KeyEvent.bKeyDown = TRUE;
+    ir.Event.KeyEvent.wVirtualKeyCode = VK_PAUSE;
+    ir.Event.KeyEvent.wRepeatCount = 1;
+  }
+
+  return 0;
+}
+
+int main()
+{
+  HANDLE hin = GetStdHandle(STD_INPUT_HANDLE);
+  HANDLE h = GetStdHandle(STD_OUTPUT_HANDLE);
+  COORD c = { 0, 0 };
+
+  DWORD mode;
+  GetConsoleMode(hin, &mode);
+  SetConsoleMode(hin, mode &
+		 ~(ENABLE_LINE_INPUT));
+
+  CreateThread(NULL, 0,
+	       pausingThread, NULL,
+	       0, NULL);
+
+  int i = 0;
+  while (true) {
+    Sleep(100);
+    printf("%d\n", ++i);
+  }
+
+  return 0;
+}