private void MainForm_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e) { int CellLength = GridLength / game.GridSize; // Make sure click was inside the grid if (e.X < GridOffset || e.X > CellLength * game.GridSize + GridOffset || e.Y < GridOffset || e.Y > CellLength * game.GridSize + GridOffset) { return; } // Find row, col of mouse press int r = (e.Y - GridOffset) / CellLength; int c = (e.X - GridOffset) / CellLength; game.Move(r, c); // Redraw grid this.Invalidate(); // Check to see if puzzle has been solved if (game.isWinner()) { //Display winner dialog box MessageBox.Show(this, "Congratulations! You've won!", "Lights Out!", MessageBoxButtons.OK, MessageBoxIcon.Information); } }