Fix Issue #78: Middle mouse click no longer sends 'C' keyboard event

The bug was caused by accessing event.key.code on a mouse event without
checking the event type first. Since SFML uses a union for events, this
read garbage data. The middle mouse button value (2) coincidentally matched
the keyboard 'C' value (2), causing the spurious keyboard event.

Fixed by adding event type check before accessing key-specific fields.
Only keyboard events (KeyPressed/KeyReleased) now trigger key callbacks.

Test added to verify middle clicks no longer generate keyboard events.

Closes #78

src/GameEngine.cpp

@@ -229,7 +229,8 @@ void GameEngine::processEvent(const sf::Event& event)
         std::string name = currentScene()->action(actionCode);
         currentScene()->doAction(name, actionType);
     }
-    else if (currentScene()->key_callable)
+    else if (currentScene()->key_callable && 
+             (event.type == sf::Event::KeyPressed || event.type == sf::Event::KeyReleased))
     {
         currentScene()->key_callable->call(ActionCode::key_str(event.key.code), actionType);
     }

tests/issue78_middle_click_fix_test.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+"""Test that Issue #78 is fixed - Middle Mouse Click should NOT send 'C' keyboard event"""
+import mcrfpy
+from mcrfpy import automation
+import sys
+
+# Track events
+keyboard_events = []
+click_events = []
+
+def keyboard_handler(key):
+    """Track keyboard events"""
+    keyboard_events.append(key)
+    print(f"Keyboard event received: '{key}'")
+    
+def click_handler(x, y, button):
+    """Track click events"""
+    click_events.append((x, y, button))
+    print(f"Click event received: ({x}, {y}, button={button})")
+
+def test_middle_click_fix(runtime):
+    """Test that middle click no longer sends 'C' key event"""
+    print(f"\n=== Testing Issue #78 Fix (runtime: {runtime}) ===")
+    
+    # Simulate middle click
+    print("\nSimulating middle click at (200, 200)...")
+    automation.middleClick(200, 200)
+    
+    # Also test other clicks for comparison
+    print("Simulating left click at (100, 100)...")
+    automation.click(100, 100)
+    
+    print("Simulating right click at (300, 300)...")
+    automation.rightClick(300, 300)
+    
+    # Wait a moment for events to process
+    mcrfpy.setTimer("check_results", check_results, 500)
+
+def check_results(runtime):
+    """Check if the bug is fixed"""
+    print(f"\n=== Results ===")
+    print(f"Keyboard events received: {len(keyboard_events)}")
+    print(f"Click events received: {len(click_events)}")
+    
+    # Check if 'C' was incorrectly triggered
+    if 'C' in keyboard_events or 'c' in keyboard_events:
+        print("\n✗ FAIL - Issue #78 still exists: Middle click triggered 'C' keyboard event!")
+        print(f"Keyboard events: {keyboard_events}")
+    else:
+        print("\n✓ PASS - Issue #78 is FIXED: No spurious 'C' keyboard event from middle click!")
+    
+    # Take screenshot
+    filename = f"issue78_fixed_{int(runtime)}.png"
+    automation.screenshot(filename)
+    print(f"\nScreenshot saved: {filename}")
+    
+    # Cleanup and exit
+    mcrfpy.delTimer("check_results")
+    sys.exit(0)
+
+# Set up test scene
+print("Setting up test scene...")
+mcrfpy.createScene("issue78_test")
+mcrfpy.setScene("issue78_test")
+ui = mcrfpy.sceneUI("issue78_test")
+
+# Register keyboard handler
+mcrfpy.keypressScene(keyboard_handler)
+
+# Create a clickable frame
+frame = mcrfpy.Frame(50, 50, 400, 400,
+                    fill_color=mcrfpy.Color(100, 150, 200),
+                    outline_color=mcrfpy.Color(255, 255, 255),
+                    outline=3.0)
+frame.click = click_handler
+ui.append(frame)
+
+# Add label
+caption = mcrfpy.Caption(mcrfpy.Vector(100, 100),
+                        text="Issue #78 Test - Middle Click",
+                        fill_color=mcrfpy.Color(255, 255, 255))
+caption.size = 24
+ui.append(caption)
+
+# Schedule test
+print("Scheduling test to run after render loop starts...")
+mcrfpy.setTimer("test", test_middle_click_fix, 1000)