Fix sketcher mode handling to prevent unintended line creation during drag operations

Major changes:
- Fixed right-click handler to directly set mode to NONE instead of relying on main app signal handling
- Added safety checks in left-click handler to prevent drawing when no draggable point is found in NONE mode
- Enhanced mode compatibility by treating Python None as SketchMode.NONE in set_mode() method
- Added comprehensive debug logging for mode changes and interaction state tracking
- Resolved integration issue where persistent constraint modes were prematurely reset by main app
- Ensured point dragging is only enabled in NONE mode, preventing accidental polyline creation

This fixes the reported issue where deactivating the line tool would still create lines when dragging,
and ensures proper mode transitions between drawing tools and selection/drag mode.

test_coordinates.py

@@ -0,0 +1,137 @@
+#!/usr/bin/env python3
+"""
+Simple test to verify coordinate systems and point detection
+"""
+
+import sys
+sys.path.append('/Volumes/Data_drive/Programming/fluency')
+
+from PySide6.QtWidgets import QApplication, QMainWindow, QVBoxLayout, QWidget, QPushButton, QHBoxLayout
+from PySide6.QtCore import Qt, QPoint
+from drawing_modules.improved_sketcher import ImprovedSketchWidget, SketchMode, Point2D
+import logging
+
+# Set up more detailed logging
+logging.basicConfig(level=logging.DEBUG, format='%(name)s - %(levelname)s - %(message)s')
+logger = logging.getLogger(__name__)
+
+class CoordinateTestWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+        self.setWindowTitle("Coordinate System Test")
+        self.resize(1000, 700)
+        
+        # Create central widget
+        central_widget = QWidget()
+        self.setCentralWidget(central_widget)
+        layout = QVBoxLayout(central_widget)
+        
+        # Create button layout
+        button_layout = QHBoxLayout()
+        
+        # Add test points button
+        add_points_btn = QPushButton("Add Points at (0,0), (100,100), (-100,-100)")
+        add_points_btn.clicked.connect(self.add_test_points)
+        button_layout.addWidget(add_points_btn)
+        
+        # Test coordinate conversion
+        test_coords_btn = QPushButton("Test Coordinate Conversion")
+        test_coords_btn.clicked.connect(self.test_coordinate_conversion)
+        button_layout.addWidget(test_coords_btn)
+        
+        layout.addLayout(button_layout)
+        
+        # Create the sketcher widget
+        self.sketcher = ImprovedSketchWidget()
+        self.sketcher.set_mode(SketchMode.NONE)
+        layout.addWidget(self.sketcher)
+        
+        # Override mouse events to add logging
+        self.original_mouse_press = self.sketcher.mousePressEvent
+        self.sketcher.mousePressEvent = self.logged_mouse_press
+        
+    def logged_mouse_press(self, event):
+        """Logged mouse press to see coordinates"""
+        viewport_pos = event.pos()
+        local_pos = self.sketcher._viewport_to_local(viewport_pos)
+        print(f"Mouse press at viewport: {viewport_pos}, local: {local_pos}")
+        
+        # Check if we can find a point near this location
+        point = self.sketcher.sketch.get_point_near(local_pos)
+        print(f"Point near click: {point}")
+        
+        # Call original method
+        return self.original_mouse_press(event)
+        
+    def add_test_points(self):
+        """Add specific test points"""
+        print("\n--- Adding test points ---")
+        
+        # Clear existing points
+        self.sketcher.sketch.points.clear()
+        
+        # Add points at specific locations
+        test_points = [
+            (0, 0, "Origin"),
+            (100, 100, "Positive quadrant"),
+            (-100, -100, "Negative quadrant"),
+            (150, -50, "Mixed quadrant")
+        ]
+        
+        for x, y, label in test_points:
+            print(f"Creating {label} point at ({x}, {y})")
+            point = Point2D(x, y)
+            
+            # Add to sketch - this will add to solver too
+            added_point = self.sketcher.sketch.add_point(point)
+            
+            print(f"  Before solver: Point at ({added_point.x}, {added_point.y})")
+            print(f"  UI point: {added_point.ui_point}")
+            
+            # Run solver to see if it changes
+            result = self.sketcher.sketch.solve_system()
+            
+            print(f"  After solver ({result}): Point at ({added_point.x}, {added_point.y})")
+            print(f"  UI point after: {added_point.ui_point}")
+            print()
+        
+        self.sketcher.update()
+        print(f"Total points in sketch: {len(self.sketcher.sketch.points)}")
+        
+    def test_coordinate_conversion(self):
+        """Test coordinate conversion functions"""
+        print("\n--- Testing coordinate conversion ---")
+        
+        # Test some viewport positions
+        test_viewport_positions = [
+            QPoint(500, 350),  # Center of widget (approximately)
+            QPoint(600, 250),  # Right and up from center
+            QPoint(400, 450),  # Left and down from center
+        ]
+        
+        for vp_pos in test_viewport_positions:
+            local_pos = self.sketcher._viewport_to_local(vp_pos)
+            back_to_viewport = self.sketcher._local_to_viewport(local_pos)
+            
+            print(f"Viewport {vp_pos} -> Local {local_pos} -> Viewport {back_to_viewport}")
+            
+            # Check if conversion is accurate
+            diff_x = abs(vp_pos.x() - back_to_viewport.x())
+            diff_y = abs(vp_pos.y() - back_to_viewport.y())
+            print(f"  Difference: ({diff_x}, {diff_y})")
+
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+    
+    window = CoordinateTestWindow()
+    window.show()
+    
+    print("\n" + "="*60)
+    print("COORDINATE SYSTEM TEST")
+    print("1. Click 'Add Points...' to create test points")
+    print("2. Click 'Test Coordinate Conversion' to test conversions") 
+    print("3. Try clicking near the points to see if they're detected")
+    print("4. Try dragging points (should work if mode is NONE)")
+    print("="*60 + "\n")
+    
+    sys.exit(app.exec())