#677 resurfaced. (master branch)

It is easy to reproduce:
Main Monitor: 300% scaling
Second Monitor: 100% scaling

Move the form from the main monitor to the secondary. Add a node. The node has wrong NodeHeight.

This happens with the following sequence:

• Parent control is scaled and its font changed
• The parent control broadcasts CM_PARENTFONTCHANGED
• The font of the VT changes as a result (ParentFont is True)
• CM_FONTCHANGED is performed by the VT
• AutoSize is called before DefaultNodeHeight is scaled. It bumps up DefaultNodeHeight
• Then DefaultNodeHeight is scaled again in ChangeScale and the damage is done.

The whole handling of ChangeScale and AutoSize is a bit of mess. For example:

• ChangeScale starts by calling ScaleForPPI. At that point ScaleForPPI does nothing. Thankfully, because it would calll ChangeScale recursively!
• Then some checking of the ScalingFlags is done which makes no sense. sfHeight is used internally to determine whether the control height needs to be scaled.
• If IsDPIChange is False I think VT should just call the inherited method and do nothing else.

I will try to simplify things, test vigorously and submit a PR.

One suggestion I have is in relation to toAutoChangeScale. Currently it does two things:

• Determines whether AutoSize "optimizes" node height
• Determines whether DPI scaling is performed.

I think it makes absolutely no sense to disable DPI scaling in a DPI aware application. Everything would look wrong. I think that toAutoChangeScale should just control the optimization of the NodeHeight. What do you think?