实现和Word标题栏类似的效果
可以看到有三种颜色:
默认时是(243, 243, 243)，鼠标进入时是这样(210, 210, 210)，鼠标按下的瞬间变为了(177, 177, 177)
4个关键事件：MouseEnter、MouseLeave、MouseDown、MouseUp
MouseEnter：在鼠标进入控件的可见部分时发生
private void pictureBox3_MouseEnter(object sender, EventArgs e) { pictureBox3.Image = Resources.MouseEnter; }
MouseLeave：在鼠标离开控件的可见部分时发生
private void pictureBox3_MouseLeave(object sender, EventArgs e) { pictureBox3.Image = Resources.默认状态; }
MouseDown：当鼠标指针在组件上方开按下箭标按钮时发生
private void pictureBox3_MouseDown(object sender, MouseEventArgs e) { pictureBox3.Image = Resources.点击; //MessageBox.Show("test OK!!"); }
MouseUp：在鼠标指针在组件上方开释放鼠标按钮时发生
private void pictureBox3_MouseUp(object sender, MouseEventArgs e) { pictureBox3.Image = Resources.MouseEnter; }
有朋友可能会问，为什么你要用pictureBox，而不是按钮+标签，那是因为我还想好怎么弄
panel+pictureBox+label
