I figured out where is the issue (and partially my mistake, as I see the red and green UV isocurves as the same colour since I’m colour-blind). While Rhino 9 WIP changes the tiny arrows, the preview does not change the newly introduced large UV indicators at the corner of the edited surface when the control points are visible. This caused my confusion and made me think that the command does nothing when I click on “SwapUV”.
Also, the name of the RMB command tooltip could be more appropriate. It is called “Analyze direction”, whereas its main purpose and ability is to change the direction (hence my proposal to change it to “Swap direction” or “SwapUV”, because it does exactly that).
Having “Flip direction” for the LMB also adds to the confusion, because the ! _Flip can flip the direction, hence the tooltip of the same name.
However, the ! _Dir command can also flip the direction with a simple LMB click, or use the command line options to swap the UV, but it’s not called “SwapUV”, or “Swap direction” or “Change direction”. The ! _Dir command is not a basic analysis tool. It’s the primary editing tool for change the normal direction and swap the UV coordinates.
Using the same logic, the “Blend surface” tool’s main purpose is to actually build a blend surface rather than just analyzing how the latter could look like. This is why it’s not called “Analyze Blend surface”.
Other confusion that I notice in the latest WIP is that when I activate the ! _ShowDir tool, the buttons on the pop-up panel are inactive (grayed-out). I’m forced to de-select the surface by clicking on a blank area in the viewport, then select it again to make the buttons clickable. Is that a bug?
In Rhino 7 the buttons are clickable even if the surface points are visible. However, when the control points are visible in V7 and I click on “SwapUV”, the buttons become inactive forever.
