It took a bit, though here's my feedback.
Generally the mesh gradient tool already works very well. So, congratulations and thank you a lot for that!
Though I have several smaller and bigger remarks on it:
- Double-clicking path with gradient tool selected causes program crash
If you select the gradient tool and double-click a path to devide a row or column, the program crashes.
- Toggling sides between beziers and lines or making them elliptical deselects them
When multiple corner nodes are selected and you toggle the sides between beziers and lines or make them elliptical, the selection of the nodes is removed. I'd expect the selection to be kept.
- Edges display update delayed
While dragging around the nodes the display of the mesh is updated immediately, though the display of the mesh sides is updated with a delay. It would be better UX if they were updated instantenously
- Alt+B doesn't work
The shortcut Alt+B to toggle the selected sides doesn't seem to work.
- Hard to distinguish nodes and handles
With the only difference being the form of the node, corner nodes and bezier handles are hard to distinguish. A different color for corner nodes (like within the vector tool) would improve that.
- Hard to associate handles with nodes
When bezier handles are near to each other it is hard to distinguish which one belongs to which corner node. Therefore bezier handles and their related corner nodes should be connected through a line like it's done within the vector tool.
- Dividing rows/columns requires a corner node to be selected
To devide a row or column through a double-click requires at least one corner node to be selected. This is an unnecessary restriction and should be lifted.
- Snapping and preserving angle via Ctrl or Ctrl+Alt doesn't work
The status message says that Ctrl allows to snap the angle and Ctrl+Alt to preserve the angle while editing the mesh (like within other tools), though they don't work.
- Status message wrong regarding Ctrl+Shift
The status message says that Ctrl+Shift allows to scale around a center, though this doesn't apply to mesh gradients, or does it?
- Mesh tool is separate from other gradients
The mesh gradient tool is just another type of gradient, so it should be part of the existing gradient tool instead of having a separate button within the toolbar.
- Linear and radial gradient tool allows to change mesh gradients but not vice versa
When the linear and radial gradient tool is selected, you can also change mesh gradients, but when the mesh gradient tool is selected, you cannot edit linear or radial gradients. This inconsistency should be removed, i.e. you should always be able to edit the gradients.
This goes hand in hand with the above idea of integrating the mesh tool into the existing gradient tool. (This also applies to conical gradients.)
- Replacing mesh gradients by another gradient type requires to switch to Fill and Stroke
Unlike when switching between linear and radial gradients, to replace a mesh gradient by another gradient, you need to switch to the Fill and Stroke dialog.
This is another part of integrating the mesh tool into the existing gradient tool. (This also applies to conical gradients.)
- Creating a mesh requires dragging
To create a mesh you need to drag the mouse a little. It would be better if a simple click would create a default mesh (spanning over the whole bounding box of the object) and dragging would allow to put up a mesh like creating an object.
- Clicking inside object hides mesh
The display of the mesh gradient is toggled when clicking inside the related object. This is different to the behavior of linear and radial gradients, which stay visible when clicking into the object. This is also an issue regarding the separation of rows and columns via double click, because the mesh gets hidden afterwards.
- Toggling tensor points only switches the colors of the selected corner nodes to a mixed color (there are no tensor handles)
There are no tensor handles displayed on Alt+G. The only thing I see is that the colors of the selected corner nodes get a mixed color applied. (Though I'm not sure how this feature is expected to work.)
- Color sampling hard to understand without example
Picking the colors from underneath the mesh is a very cool feature, though it took me a bit to understand how it works. I'm not sure whether this can be removed in the UI, but this should at least be described in more detail within the wiki.
- Show shortcuts in button tooltips
Several buttons within the mesh toolbar have shortcuts applied. Those shortcuts should be displayed within their tooltips.