We'll continue here the program started in example 14.

Currently, when we turn the first checkbox on and press the "capture" button, we can't click on the "cancel" properly since the timer is constantly re-focusing back on the "capture" button. We should be able to click on the "cancel" button normally.

Let's create a whole new sub for button2. Below all subs in the coding page, add this:
Private Sub Button2_Mouse(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.MouseMove, Button2.MouseLeave
End Sub

-> the name of the sub is gonna be: Button2_Mouse. The arguments it holds (the variables) can be copied from other subs. At the very end we add two events: MouseMove and MouseLeave

Inside the sub we will add this:

If Button2.Focused = True Then
Button1.Focus()
Label1.Text = "! Scroll with your mouse and then press Space !"
AddHandler Button2.MouseMove, AddressOf Button2_MouseMove
Exit Sub
End If
        
If Button2.Visible = True Then
Button2.Focus()
Label1.Text = "Cancel button selected"
RemoveHandler Button2.MouseMove, AddressOf Button2_MouseMove
End If

This sub registers two events MouseMove - sub gets triggered when you cause mouse movement over the object, while MouseLeave - triggers the code of the sub when you leave the object with your mouse cursor.

First we check the second "if" statement, since it's the first operation that gets started. 
What we wanted to achieve: after we press the "capture" button, we scroll over onto the "cancel" button, we trigger the MouseMove event and start the sub operations: the focus will get transferred to button2 and label text will be changed. We then remove the MouseMove event so that it no longer starts the sub. The only event that will now trigger it again is leaving button2 with your mouse cursor. 

The first "if" statement -> if you decide not to press the "cancel" button and move away, then you'll return the focus on button1, label is reset and we add the MouseMove event back to the sub again.

The second "if" statement might appear as unnecessary but if it's removed (and the code inside is kept) then after you click on the "cancel" button, the program will return to this sub again (very quickly) and do two code lines again -> which is not supposed to happen. The presence of the second "if" statement stops that.

After we remove the MouseMove event we can either proceed by moving away from the "cancel" button or by clicking on it. Both of those choices must return the MouseMove event back. That's why we have to go back to the "Button2_Click" sub and this at the bottom:
AddHandler Button2.MouseMove, AddressOf Button2_Mouse

The timer will be still fighting against our choice to transfer the focus on the "cancel" button at the moment. We need to go to the timer sub and change this line:
If Button2.Visible = True Then
into:
If Button2.Visible = True And Button2.Focused = False Then

-> so we're saying to the timer: only focus back on the "capture" button IF the "cancel" button is not focused.

Code:

    Public Class Form1

    Private x1 As Integer
    Private gg As String()

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    If Button2.Visible = True Then
    x1 = x1 + 1
    Label1.Text = ""
    Button2.Visible = False
    Label1.Focus()
    Exit Sub
    End If
    If CheckBox1.Checked Or CheckBox2.Checked Or CheckBox3.Checked Then
    Label1.Text = "! Scroll with your mouse and then press Space !"
    Button2.Visible = True
    End If
    End Sub

    Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
    If CheckBox1.Checked Then
    Timer1.Enabled = True
    Else
    Timer1.Enabled = False
    End If
    If CheckBox1.Checked = False Then
    gg(x1) = ""
    TextBox1.Lines = gg
    End If
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    If CheckBox1.Checked Then
    ReDim Preserve gg(0 To x1)
    gg(x1) = Cursor.Position.ToString
    TextBox1.Lines = gg
    End If
    If Button2.Visible = True And Button2.Focused = False Then
    Button1.Focus()
    End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    Button2.Visible = False
    Label1.Text = ""
    AddHandler Button2.MouseMove, AddressOf Button2_Mouse
    End Sub
   
    Private Sub Button2_Mouse(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.MouseMove, Button2.MouseLeave
    If Button2.Focused = True Then
    Button1.Focus()
    Label1.Text = "! Scroll with your mouse and then press Space !"
    AddHandler Button2.MouseMove, AddressOf Button2_Mouse
    Exit Sub
    End If

    If Button2.Visible = True Then
    Button2.Focus()
    Label1.Text = "Cancel button selected"
    RemoveHandler Button2.MouseMove, AddressOf Button2_Mouse
    End If
    End Sub

    End Class


The program should work for the first checkbox. Adding the other two ones is quite simple. Each checkbox will have it's two variables just like the first option.

The most important part to notice is how we get the values for the other coordinates.
Inside the Timer1 sub we will have this line for checkbox2 - Form + Borders.
kk(x2) = ((Cursor.Position - Bounds.Location).ToString)

Bounds:Location - contains both x and y values. This is the location of the top-left pixel of the main field form on the whole computer screen. The value of "Bounds.Location" changes only when we drag the main form around our computer screen. Try to get the second textbox on (0,0) and then check the coordinates inside the first textbox -> those are gonna be the location values of the form bounds. Those are gonna be reduced from the whole screen coordinates in every moment to give you the results in checkbox2.

Third option (inside timer):
nn(x3) = PointToClient(Cursor.Position).ToString

-> this gives you coordinates relative to the main field form while neglecting the borders of the form.

Final code:

    Public Class Form1

    Private x1 As Integer
    Private x2 As Integer
    Private x3 As Integer

    Private gg As String()
    Private kk As String()
    Private nn As String()

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    If Button2.Visible = True Then
    If CheckBox1.Checked Then
    x1 = x1 + 1
    End If
    If CheckBox2.Checked Then
    x2 = x2 + 1
    End If
    If CheckBox3.Checked Then
    x3 = x3 + 1
    End If
    Label1.Text = ""
    Button2.Visible = False
    Label1.Focus()
    Exit Sub
    End If
    If CheckBox1.Checked Or CheckBox2.Checked Or CheckBox3.Checked Then
    Label1.Text = "! Scroll with your mouse and then press Space !"
    Button2.Visible = True
    End If
    End Sub

    Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
    If CheckBox1.Checked = False Then
    gg(x1) = ""
    TextBox1.Lines = gg
    End If
    enabl()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    If CheckBox1.Checked Then
    ReDim Preserve gg(0 To x1)
    gg(x1) = Cursor.Position.ToString
    TextBox1.Lines = gg
    End If
    If CheckBox2.Checked Then
    ReDim Preserve kk(0 To x2)
    kk(x2) = ((Cursor.Position - Bounds.Location).ToString)
    TextBox2.Lines = kk
    End If
    If CheckBox3.Checked Then
    ReDim Preserve nn(0 To x3)
    nn(x3) = PointToClient(Cursor.Position).ToString
    TextBox3.Lines = nn
    End If

    If Button2.Visible = True And Button2.Focused = False Then
    Button1.Focus()
    End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    Button2.Visible = False
    Label1.Text = ""
    AddHandler Button2.MouseMove, AddressOf Button2_Mouse
    End Sub

    Private Sub Button2_Mouse(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.MouseMove, Button2.MouseLeave
    If Button2.Focused = True Then
    Button1.Focus()
    Label1.Text = "! Scroll with your mouse and then press Space !"
    AddHandler Button2.MouseMove, AddressOf Button2_Mouse
    Exit Sub
    End If

    If Button2.Visible = True Then
    Button2.Focus()
    Label1.Text = "Cancel button selected"
    RemoveHandler Button2.MouseMove, AddressOf Button2_Mouse
    End If
    End Sub

    Private Sub CheckBox2_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox2.CheckedChanged
    If CheckBox2.Checked = False Then
    kk(x2) = ""
    TextBox2.Lines = kk
    End If
    enabl()
    End Sub

    Private Sub CheckBox3_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox3.CheckedChanged
    If CheckBox3.Checked = False Then
    nn(x3) = ""
    TextBox3.Lines = nn
    End If
    enabl()
    End Sub

    Sub enabl()
    If CheckBox1.Checked = False And CheckBox2.Checked = False And CheckBox3.Checked = False Then
    Timer1.Enabled = False
    Else
    Timer1.Enabled = True
    End If
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
    TextBox1.Clear()
    x1 = 0
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
    TextBox2.Clear()
    x2 = 0
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
    TextBox3.Clear()
    x3 = 0
    End Sub
    End Class


enabl() - this is a sub used to check if all the checkboxes are turned off, when they are (only then!) the timer is disabled. If any of the checkboxes is turned on, the timer gets turned on too.
- all three of the checkbox subs have an enabl() call

Buttons 3, 4, 5 are the "Clear" buttons below the textboxes.

If you want a quicker check of the timer, go to design page -> Timer1 -> Properties -> change interval to 10.

I hope everything makes sense. Program should work.
There probably might be ways to somewhat shorten the code too.