Il linguaggio è visual basic però non so se si riferisce a c++ e poi non sono ferratissimo
Il codice finoscritto è questo che segue:

Public Class Form1

Dim value As String
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Interval = 30
Timer1.Enabled = False
ProgressBar1.Minimum = 0
ProgressBar1.Maximum = 50
ProgressBar1.Value = 0

End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
ProgressBar1.Value += 1
If ProgressBar1.Value = ProgressBar1.Maximum Then
ProgressBar1.Value = 0
End If
End Sub

Private Sub Button1_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseEnter

Timer1.Enabled = True
ProgressBar1.Value = 0


End Sub

Private Sub Button1_MouseLeave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseLeave
Timer1.Enabled = False
End Sub

Grazie per l'aiuto sono disperato è per la tesi!!!!