graphics/, lib/libnx, include/nutt/nx: Add support for modal windows.

include/nuttx/nx/nx.h

@@ -653,7 +653,7 @@ int nx_raise(NXWINDOW hwnd);
  *   Lower the specified window to the bottom of the display.
  *
  * Input Parameters:
- *   hwnd - the window to be lowered
+ *   hwnd - The window to be lowered
  *
  * Returned Value:
  *   OK on success; ERROR on failure with errno set appropriately
@@ -662,6 +662,24 @@ int nx_raise(NXWINDOW hwnd);
 
 int nx_lower(NXWINDOW hwnd);
 
+/****************************************************************************
+ * Name: nx_modal
+ *
+ * Description:
+ *   May be used to either (1) raise a window to the top of the display and
+ *   select modal behavior, or (2) disable modal behavior.
+ *
+ * Input Parameters:
+ *   hwnd  - The window to be modified
+ *   modal - True: enter modal state; False: leave modal state
+ *
+ * Returned Value:
+ *   OK on success; ERROR on failure with errno set appropriately
+ *
+ ****************************************************************************/
+
+int nx_modal(NXWINDOW hwnd, bool modal);
+
 /****************************************************************************
  * Name: nx_setpixel
  *

include/nuttx/nx/nxbe.h

@@ -67,13 +67,16 @@
 /* Window flags and helper macros:
  *
  * NXBE_WINDOW_BLOCKED   - Window input is blocked (internal use only)
+ * NXBE_WINDOW_FRAMED    - Framed (NxTK) Window
  * NXBE_WINDOW_RAMBACKED - Window is backed by a framebuffer
+ * NXBE_WINDOW_MODAL     - Window is in a focused, modal state
  */
 
-#define NXBE_WINDOW_BLOCKED   (1 << 0) /* The window is blocked and will not
-                                        * receive further input. */
-#define NXBE_WINDOW_FRAMED    (1 << 1) /* Framed (NxTK) Window */
-#define NXBE_WINDOW_RAMBACKED (1 << 2) /* Window is backed by a framebuffer */
+#define NXBE_WINDOW_BLOCKED   (1 << 0) /* Bit 0: The window is blocked and will
+                                        *        not receive further input. */
+#define NXBE_WINDOW_FRAMED    (1 << 1) /* Bit 1: Framed (NxTK) Window */
+#define NXBE_WINDOW_RAMBACKED (1 << 2) /* Bit 2: Window is backed by a framebuffer */
+#define NXBE_WINDOW_MODAL     (1 << 3) /* Bit 3: Window is in a focused, modal state */
 
 /* Valid user flags for different window types */
 
@@ -110,6 +113,13 @@
 #define NXBE_CLRRAMBACKED(wnd) \
   do { (wnd)->flags &= ~NXBE_WINDOW_RAMBACKED; } while (0)
 
+#define NXBE_ISMODAL(wnd) \
+  (((wnd)->flags & NXBE_WINDOW_MODAL) != 0)
+#define NXBE_SETMODAL(wnd) \
+  do { (wnd)->flags |= NXBE_WINDOW_MODAL; } while (0)
+#define NXBE_CLRMODAL(wnd) \
+  do { (wnd)->flags &= ~NXBE_WINDOW_MODAL; } while (0)
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/

include/nuttx/nx/nxmu.h

@@ -147,6 +147,7 @@ enum nxmsg_e
   NX_SVRMSG_GETPOSITION,      /* Get the current window position and size */
   NX_SVRMSG_RAISE,            /* Move the window to the top */
   NX_SVRMSG_LOWER,            /* Move the window to the bottom */
+  NX_SVRMSG_MODAL,            /* Select/de-slect window modal state */
   NX_SVRMSG_SETPIXEL,         /* Set a single pixel in the window with a color */
   NX_SVRMSG_FILL,             /* Fill a rectangle in the window with a color */
   NX_SVRMSG_GETRECTANGLE,     /* Get a rectangular region in the window */
@@ -350,7 +351,18 @@ struct nxsvrmsg_raise_s
 struct nxsvrmsg_lower_s
 {
   uint32_t msgid;                  /* NX_SVRMSG_LOWER */
-  FAR struct nxbe_window_s *wnd;   /* The window to be lowered  */
+  FAR struct nxbe_window_s *wnd;   /* The window to be lowered */
+};
+
+/* This message either (1) raises a window to the top of the display and
+ * selects the modal state, or (2) de-selects the modal state.
+ */
+
+struct nxsvrmsg_modal_s
+{
+  uint32_t msgid;                  /* NX_SVRMSG_MODAL */
+  FAR struct nxbe_window_s *wnd;   /* The window to be modified */
+  bool modal;                      /* True: enter modal state; False: leave modal state */
 };
 
 /* Set a single pixel in the window with a color */

include/nuttx/nx/nxtk.h

@@ -328,6 +328,24 @@ int nxtk_raise(NXTKWINDOW hfwnd);
 
 int nxtk_lower(NXTKWINDOW hfwnd);
 
+/****************************************************************************
+ * Name: nxtk_modal
+ *
+ * Description:
+ *   May be used to either (1) raise a window to the top of the display and
+ *   select modal behavior, or (2) disable modal behavior.
+ *
+ * Input Parameters:
+ *   hfwnd - The window to be modified
+ *   modal - True: enter modal state; False: leave modal state
+ *
+ * Returned Value:
+ *   OK on success; ERROR on failure with errno set appropriately
+ *
+ ****************************************************************************/
+
+int nxtk_modal(NXTKWINDOW hfwnd, bool modal);
+
 /****************************************************************************
  * Name: nxtk_fillwindow
  *