make user aware of grab mouse limitations

src/emucore/EventHandler.cxx

@@ -566,9 +566,12 @@ void EventHandler::handleEvent(Event::Type event, Int32 value, bool repeated)
     case Event::ToggleGrabMouse:
       if (pressed && !repeated && !myOSystem.frameBuffer().fullScreen())
       {
+        bool oldState = myOSystem.frameBuffer().grabMouseEnabled();
         myOSystem.frameBuffer().toggleGrabMouse();
-        myOSystem.frameBuffer().showMessage(myOSystem.frameBuffer().grabMouseEnabled()
-                                            ? "Grab mouse enabled" : "Grab mouse disabled");
+        bool newState = myOSystem.frameBuffer().grabMouseEnabled();
+        myOSystem.frameBuffer().showMessage(oldState != newState ? myOSystem.frameBuffer().grabMouseEnabled()
+                                            ? "Grab mouse enabled" : "Grab mouse disabled"
+                                            : "Grab mouse not allowed while cursor shown");
       }
       return;
 

src/emucore/FrameBuffer.cxx

@@ -843,16 +843,27 @@ void FrameBuffer::setCursorState()
        myOSystem.console().rightController().isAnalog()) : false;
   bool alwaysUseMouse = BSPF::equalsIgnoreCase("always", myOSystem.settings().getString("usemouse"));
 
-  grabMouse(emulation && (analog || alwaysUseMouse) && myGrabMouse);
-
   // Show/hide cursor in UI/emulation mode based on 'cursor' setting
-  switch(myOSystem.settings().getInt("cursor"))
+  int cursor = myOSystem.settings().getInt("cursor");
+  switch(cursor)
   {
-    case 0: showCursor(false);      break;
-    case 1: showCursor(emulation);  break;
-    case 2: showCursor(!emulation); break;
-    case 3: showCursor(true);       break;
+    case 0:
+      showCursor(false);
+      break;
+    case 1:
+      showCursor(emulation);
+      myGrabMouse = false; // disable grab while cursor is shown in emulation
+      break;
+    case 2:
+      showCursor(!emulation);
+      break;
+    case 3:
+      showCursor(true);
+      myGrabMouse = false; // disable grab while cursor is shown in emulation
+      break;
   }
+
+  grabMouse(emulation && (analog || alwaysUseMouse) && myGrabMouse);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/gui/InputDialog.cxx

@@ -129,7 +129,7 @@ void InputDialog::addDevicePortTab(const GUI::Font& font)
   VarList::push_back(items, "+UI, -Emulation", "2");
   VarList::push_back(items, "+UI, +Emulation", "3");
   myCursorState = new PopUpWidget(myTab, font, HBORDER, ypos, pwidth, lineHeight, items,
-                                  "Mouse cursor visibility ", lwidth);
+                                  "Mouse cursor visibility ", lwidth, kCursorStateChanged);
   wid.push_back(myCursorState);
 #ifndef WINDOWED_SUPPORT
   myCursorState->clearFlags(Widget::FLAG_ENABLED);
@@ -272,6 +272,7 @@ void InputDialog::loadConfig()
 
   // Mouse cursor state
   myCursorState->setSelected(instance().settings().getString("cursor"), "2");
+  handleCursorState();
 
   // Joystick deadzone
   myDeadzone->setValue(instance().settings().getInt("joydeadzone"));
@@ -280,7 +281,7 @@ void InputDialog::loadConfig()
   // Paddle speed (digital and mouse)
   myDejitterBase->setValue(instance().settings().getInt("dejitter.base"));
   myDejitterDiff->setValue(instance().settings().getInt("dejitter.diff"));
-  UpdateDejitter();
+  updateDejitter();
   myDPaddleSpeed->setValue(instance().settings().getInt("dsense"));
   myDPaddleLabel->setLabel(instance().settings().getString("dsense"));
   myMPaddleSpeed->setValue(instance().settings().getInt("msense"));
@@ -365,8 +366,12 @@ void InputDialog::saveConfig()
   // Grab mouse and hide cursor
   const string& cursor = myCursorState->getSelectedTag().toString();
   instance().settings().setValue("cursor", cursor);
-  instance().settings().setValue("grabmouse", myGrabMouse->getState());
-  instance().frameBuffer().enableGrabMouse(myGrabMouse->getState());
+  // only allow grab mouse if cursor is hidden in emulation
+  int state = myCursorState->getSelected();
+  bool enableGrab = state != 1 && state != 3;
+  bool grab = enableGrab ? myGrabMouse->getState() : false;
+  instance().settings().setValue("grabmouse", grab);
+  instance().frameBuffer().enableGrabMouse(grab);
 
   // Enable/disable modifier key-combos
   instance().settings().setValue("modcombo", myModCombo->getState());
@@ -416,7 +421,7 @@ void InputDialog::setDefaults()
       myDejitterBase->setValue(0);
       myDejitterDiff->setValue(0);
     #endif
-      UpdateDejitter();
+      updateDejitter();
       myTrackBallSpeed->setValue(10);
       myTrackBallLabel->setLabel("10");
 
@@ -432,6 +437,8 @@ void InputDialog::setDefaults()
       // Enable/disable modifier key-combos
       myModCombo->setState(true);
 
+      handleCursorState();
+
       break;
     }
 
@@ -559,6 +566,10 @@ void InputDialog::handleCommand(CommandSender* sender, int cmd,
       setDefaults();
       break;
 
+    case kCursorStateChanged:
+      handleCursorState();
+      break;
+
     case kDeadzoneChanged:
       myDeadzoneLabel->setValue(3200 + 1000*myDeadzone->getValue());
       break;
@@ -572,7 +583,7 @@ void InputDialog::handleCommand(CommandSender* sender, int cmd,
       break;
 
     case kDejitterChanged:
-      UpdateDejitter();
+      updateDejitter();
       break;
 
     case kTBSpeedChanged:
@@ -618,7 +629,16 @@ void InputDialog::handleCommand(CommandSender* sender, int cmd,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void InputDialog::UpdateDejitter()
+void InputDialog::handleCursorState()
+{
+  int state = myCursorState->getSelected();
+  bool enableGrab = state != 1 && state != 3;
+
+  myGrabMouse->setEnabled(enableGrab);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void InputDialog::updateDejitter()
 {
   int strength = myDejitterBase->getValue();
   stringstream label;

src/gui/InputDialog.hxx

@@ -61,19 +61,21 @@ class InputDialog : public Dialog
 
     void addDevicePortTab(const GUI::Font& font);
 
+    void handleCursorState();
+    void updateDejitter();
     void eraseEEPROM();
-    void UpdateDejitter();
 
   private:
     enum {
-      kDeadzoneChanged   = 'DZch',
-      kDejitterChanged   = 'Pjch',
-      kDPSpeedChanged    = 'PDch',
-      kMPSpeedChanged    = 'PMch',
-      kTBSpeedChanged    = 'TBch',
-      kDBButtonPressed   = 'DBbp',
-      kEEButtonPressed   = 'EEbp',
-      kConfirmEEEraseCmd = 'EEcf'
+      kCursorStateChanged = 'CSch',
+      kDeadzoneChanged    = 'DZch',
+      kDejitterChanged    = 'Pjch',
+      kDPSpeedChanged     = 'PDch',
+      kMPSpeedChanged     = 'PMch',
+      kTBSpeedChanged     = 'TBch',
+      kDBButtonPressed    = 'DBbp',
+      kEEButtonPressed    = 'EEbp',
+      kConfirmEEEraseCmd  = 'EEcf'
     };
 
     TabWidget* myTab{nullptr};