Control Not Redrawn On Me.Invalidate()

I call Me.Invalidate() in the property setter of a custom control (inherits from ProgressBar) but it only causes the control to paint on screen about 1 in every 10 times (or less) whereas there are far more times that the code enters the painting routines (i.e. only on some occassions do the painting routines cause on screen changes). I am using my own Painting routines, not using ProgressBarRenderer.

On the Inherited ProgressBar I set Minimum to 0 and Maximum to 1000 and use a timer to increment Value by 1 on each tick (100ms). Therefore Me.Invalidate() should be called after every tick and hence the 'progress' of the bar should be quite smooth - 1000 small increments as it fills the bar should be pretty small changes and hence appear fairly smooth.

However, what happens is that the control only changes on screen about 1 in 10 of the times that Value changes. The control also writes the progress as a % (integer) onto its surface and each change in the % text is accompanied by an increase in the visual progress. I think this apparent synchronisation is coincidence though, since using Console.WriteLine I can see many many calls to the Painting routine but a few of them actually cause a visual change on screen.

I have tried slowing the timer down to 1000ms but this hasn't changed anything other than there are far more than 10 calls to the painting routines between actual on screen changes.

I am using PointF, RectangleF and SizeF to avoid 'rounding errors' and hence blocky progress from using the Integer versions of those structures.

There's some stuff from the Output window (using Console.Writeline) near the bottom of this post that shows that at the beginning there is 1 OnPaint per Invalidate. Later on (somewhere around 1% and 5% progress) it changes to having several OnPaint calls between Invalidates. So I certainly don't appear to be short on calls to OnPaint. I only appear to be short of actual OnScreen changes.

The Painting routines use the RectangleF structures to create GraphicsPath objects, which are used to create a Region that is then filled by e.Graphics.FillRegion.

Possibilities I can think of:

1) The painting events are too frequent to allow screen udpating, but this doesn't seem likely since 1000ms timer ticks didn't help

2) GraphicsPath and / or Region objects aren't 'precise' and hence a range of similarly sized RectangleF objects create essentially identical GraphicsPath objects (or the same problem when moving from GraphicsPath to Region)

3) Erm, not sure...

Here's the Setter code:

Public Shadows Property Value As Integer
Get
Value = MyBase.Value

[Code].....