show a toast when hint can't find anything, on the principle that user

should see some response to every action.

xwords4/android/XWords4/archive/R.java

@@ -2444,6 +2444,7 @@ public final class R {
          placed, i.e. they do not form a single word. 
          */
         public static final int str_no_empties_in_turn=0x7f05017f;
+        public static final int str_no_hint_found=0x7f050313;
         /**  Same as above, but used when you try to show tiles belonging
          to a player on another device (a remote player.) 
          */

xwords4/android/XWords4/res/values/strings.xml

@@ -2526,4 +2526,6 @@
   <string name="not_again_comms_bt">Use Bluetooth to play against a
   nearby device that\'s \"paired\" with yours.</string>
 
+  <string name="str_no_hint_found">Cannot find any moves</string>
+
 </resources>

xwords4/android/XWords4/res_src/values-ba_CK/strings.xml

@@ -2184,4 +2184,5 @@
   i.e. yreve reirrac ni eht dlrow tpecxe Nozirev dna Tnirps.</string>
   <string name="not_again_comms_bt">Esu Htooteulb ot yalp tsniaga a
   ybraen ecived taht\'s \"deriap\" htiw sruoy.</string>
+  <string name="str_no_hint_found">Tonnac dnif yna sevom</string>
 </resources>

xwords4/android/XWords4/res_src/values-ca_PS/strings.xml

@@ -2184,4 +2184,5 @@
   I.E. EVERY CARRIER IN THE WORLD EXCEPT VERIZON AND SPRINT.</string>
   <string name="not_again_comms_bt">USE BLUETOOTH TO PLAY AGAINST A
   NEARBY DEVICE THAT\'S \"PAIRED\" WITH YOURS.</string>
+  <string name="str_no_hint_found">CANNOT FIND ANY MOVES</string>
 </resources>

xwords4/android/XWords4/src/org/eehouse/android/xw4/BoardDelegate.java

@@ -1733,6 +1733,7 @@ public class BoardDelegate extends DelegateBase
         public void userError( int code )
         {
             int resid = 0;
+            boolean asToast = false;
             switch( code ) {
             case UtilCtxt.ERR_TILES_NOT_IN_LINE:
                 resid = R.string.str_tiles_not_in_line;
@@ -1778,10 +1779,23 @@ public class BoardDelegate extends DelegateBase
             case ERR_REG_SERVER_SANS_REMOTE:
                 resid = R.string.str_reg_server_sans_remote;
                 break;
+            case ERR_NO_HINT_FOUND:
+                resid = R.string.str_no_hint_found;
+                asToast = true;
+                break;
             }
 
             if ( resid != 0 ) {
-                nonBlockingDialog( DlgID.DLG_OKONLY, getString( resid ) );
+                if ( asToast ) {
+                    final int residf = resid;
+                    runOnUiThread( new Runnable() {
+                            public void run() {
+                                showToast( residf );
+                            }
+                        } );
+                } else {
+                    nonBlockingDialog( DlgID.DLG_OKONLY, getString( resid ) );
+                }
             }
         } // userError
 

xwords4/android/XWords4/src/org/eehouse/android/xw4/jni/UtilCtxt.java

@@ -125,7 +125,9 @@ public interface UtilCtxt {
     static final int ERR_NO_EMPTY_TRADE = 13;
     static final int ERR_CANT_UNDO_TILEASSIGN = 14;
     static final int ERR_CANT_HINT_WHILE_DISABLED = 15;
-    static final int ERR_RELAY_BASE = 16;
+    static final int ERR_NO_HINT_FOUND = 16;
+
+    static final int ERR_RELAY_BASE = 17;
     void userError( int id );
 
     void informMove( String expl, String words );

xwords4/common/board.c

@@ -2121,6 +2121,8 @@ board_requestHint( BoardCtxt* board,
                 }
                 setArrowVisible( board, wasVisible );
             }
+        } else {
+            util_userError( board->util, ERR_NO_HINT_FOUND );
         }
     }
     return result || redraw;

xwords4/common/util.h

@@ -58,6 +58,7 @@ typedef enum {
 /*     ERR_NOT_YOUR_TURN_TO_MOVE, */
     ERR_CANT_UNDO_TILEASSIGN,
     ERR_CANT_HINT_WHILE_DISABLED,
+    ERR_NO_HINT_FOUND,          /* not really an error... */
 
     ERR_RELAY_BASE,
     ERR_RELAY_END = ERR_RELAY_BASE + XWRELAY_ERROR_LASTERR

xwords4/linux/linuxutl.c

@@ -492,6 +492,10 @@ linux_getErrString( UtilErrID id, XP_Bool* silent )
         message = "No tiles selected; trade cancelled.";
         break;
 
+    case ERR_NO_HINT_FOUND:
+        message = "Unable to suggest any moves.";
+        break;
+
     case ERR_CANT_UNDO_TILEASSIGN:
         message = "Tile assignment can't be undone.";
         break;