win32: disable quickedit mode when enabling mouse support

The Windows conpty layer now allows terminal emulators other
than the classic conhost.exe to host win32 console applications that
use mouse events.

For mouse events to function correctly, mouse input needs to be
enabled and quick edit mode needs to be disabled.

This commit teaches vim to make this change when it enables mouse
mode.

I have no special knowledge of vim, and this patch is roughly based
on the suggested changes in this discussion:

https://groups.google.com/g/vim_dev/c/bQ7jfMwa8Zg

The intent is to enable mouse input and disable quickedit when
enabling mouse mode, and to disable mouse input and restore the
prior quickedit mode state when mouse mode is disabled.

refs: microsoft/terminal#9970

src/os_win32.c

@@ -1165,6 +1165,7 @@ decode_key_event(
 
 #endif // FEAT_GUI_MSWIN
 
+static DWORD g_cmodein = 0;
 
 /*
  * For the GUI the mouse handling is in gui_w32.c.
@@ -1200,9 +1201,15 @@ mch_setmouse(int on)
     GetConsoleMode(g_hConIn, &cmodein);
 
     if (g_fMouseActive)
+    {
 	cmodein |= ENABLE_MOUSE_INPUT;
+	cmodein &= ~ENABLE_QUICK_EDIT_MODE;
+    }
     else
+    {
 	cmodein &= ~ENABLE_MOUSE_INPUT;
+	cmodein |= g_cmodein & ENABLE_QUICK_EDIT_MODE;
+    }
 
     SetConsoleMode(g_hConIn, cmodein);
 }
@@ -2782,7 +2789,6 @@ SaveConsoleTitleAndIcon(void)
 static int g_fWindInitCalled = FALSE;
 static int g_fTermcapMode = FALSE;
 static CONSOLE_CURSOR_INFO g_cci;
-static DWORD g_cmodein = 0;
 static DWORD g_cmodeout = 0;
 
 /*
@@ -3747,7 +3753,14 @@ mch_settmode(tmode_T tmode)
 	cmodein &= ~(ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT |
 		     ENABLE_ECHO_INPUT);
 	if (g_fMouseActive)
+	{
 	    cmodein |= ENABLE_MOUSE_INPUT;
+	    cmodein &= ~ENABLE_QUICK_EDIT_MODE;
+	}
+	else
+	{
+	    cmodein |= g_cmodein & ENABLE_QUICK_EDIT_MODE;
+	}
 	cmodeout &= ~(
 # ifdef FEAT_TERMGUICOLORS
 	    // Do not turn off the ENABLE_PROCESSED_OUTPUT flag when using
@@ -5621,9 +5634,15 @@ termcap_mode_start(void)
 
     GetConsoleMode(g_hConIn, &cmodein);
     if (g_fMouseActive)
+    {
 	cmodein |= ENABLE_MOUSE_INPUT;
+	cmodein &= ~ENABLE_QUICK_EDIT_MODE;
+    }
     else
+    {
 	cmodein &= ~ENABLE_MOUSE_INPUT;
+	cmodein |= g_cmodein & ENABLE_QUICK_EDIT_MODE;
+    }
     cmodein |= ENABLE_WINDOW_INPUT;
     SetConsoleMode(g_hConIn, cmodein);
 
@@ -5650,6 +5669,7 @@ termcap_mode_end(void)
 
     GetConsoleMode(g_hConIn, &cmodein);
     cmodein &= ~(ENABLE_MOUSE_INPUT | ENABLE_WINDOW_INPUT);
+    cmodein |= g_cmodein & ENABLE_QUICK_EDIT_MODE;
     SetConsoleMode(g_hConIn, cmodein);
 
 # ifdef FEAT_RESTORE_ORIG_SCREEN