// Assumes an event handler for the MouseLeftbuttonUp
// event is defined for a control named 'IncreaseQuota'
// In the control's XAML: MouseLeftButtonUp="IncreaseQuota_OnLeftMouseButtonUp"

// User first selects UI to increase the quota.
public void IncreaseQuota_OnClick(object sender, MouseEventArgs e)
{

    // Obtain an isolated store for an application.
    try
    {
        using (var store = IsolatedStorageFile.GetUserStoreForApplication())
        {
            // Request 5MB more space in bytes.
            Int64 spaceToAdd = 5242880;
            Int64 curAvail = store.AvailableFreeSpace;

            // If available space is less than
            // what is requested, try to increase.
            if (curAvail < spaceToAdd)
            {

                // Request more quota space.
                if (!store.TryIncreaseQuotaTo(store.Quota + spaceToAdd))
                {
                    // The user clicked NO to the
                    // host's prompt to approve the quota increase.
                }
                else
                {
                    // The user clicked YES to the
                    // host's prompt to approve the quota increase.
                }
            }
        }
    }

    catch (IsolatedStorageException)
    {
        // TODO: Handle that store could not be accessed.

    }
}

' Assumes an event handler for the MouseLeftbuttonUp
' event is defined for a control named 'IncreaseQuota'
' In the control's XAML: MouseLeftButtonUp="IncreaseQuota_OnLeftMouseButtonUp"
Public Sub IncreaseQuota_OnClick(ByVal sender As Object, ByVal e As MouseEventArgs)
    ' Obtain an isolated store for an application.
    Try
        Using store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
            ' Request 5MB more space in bytes.
            Dim spaceToAdd As Int64 = 5242880
            Dim curAvail As Int64 = store.AvailableFreeSpace
            ' If available space is less than
            ' what is requested, try to increase.
            If (curAvail < spaceToAdd) Then
                ' Request more quota space.
                If Not store.TryIncreaseQuotaTo((store.Quota + spaceToAdd)) Then
                    ' The user clicked NO to the
                    ' host's prompt to approve the quota increase.
                Else
                    ' The user clicked YES to the
                    ' host's prompt to approve the quota increase.
                End If
            End If
        End Using
    Catch Ex As IsolatedStorageException

        ' TODO: Handle that store could not be accessed.
    End Try
End Sub