Can't upgrade canals

[wlindley]

With the latest 11.x from git, and since quite some time now, it is not possible to upgrade a canal.  Nor is it possible to build a canal over a river, nor can the public player upgrade a river. Very frustrating now that I'm in 1811 and trying to deal with burgeoning goods demand.

[jamespetts]

It should be possible to upgrade them by holding down CTRL when dragging over them.

Edit: The reason for this is that the higher rated canals have prohibitive constraints that the lower rated canals do not have, so are is classed as a downgrade. This in fact does not have the effect of a downgrade because every water craft that can use (has a prohibitive constraint for) the smaller canals can use (also has a prohibitive constraint for) the larger canals, but there is no way of the way building code to know this. Any suggestions as to how to make this part of things easier would be appreciated.

[MCollett]

It should be possible to upgrade them by holding down CTRL when dragging over them.

This works, but (because of the dual role of 'control' in this context) has the irritating consequence that you can only upgrade straight stretches, which tend to be rather short in a river bed.

Best wishes,
Matthew

[jamespetts]

Hmm - it is difficult to know what to do about this, as there is no other way of providing different types of canal without having one prohibitive constraint each and multiple constraints on the boats.

What are people's views on disabling the prohibitive constraint check in determining whether the way in question counts as an upgrade or not?