A lot of times a mask is only used to add a quick shadow or a pattern to an artwork, after the artwork is essentially done. It's a common thing when making vector art, but there are several steps and it's not fast, and those steps also involve creating a group layer.
I have an idea how to speed things up, and the idea involves keeping everything on ONE LAYER.
The trick is to make the name of a shape decide if the shape is masked.
For example, if the first four letters of a shape's name is "mask," then the shape will be masked, while the other shapes in the layer will combine to define the visible area. Make sense?
So, for example, if a person creates a new vector layer and then creates a red apple with a stem and a leaf and this artwork takes 5 shapes total (on one layer), and now the person wants to add a shadow, all they would need to do is create a big shadow shape that goes beyond the apple art, name the shape "mask-1" or "mask-apple" or whatever, and the shadow would be masked! The part of the shadow that extends beyond the apple would not be visible.
Under layer settings, there could be a checkbox for stroke visibility, but the default would be "exclude strokes," since that's more common (I'm guessing).
This idea is not intended to suggest that the usual masking process needs to be replaced - not at all. This idea is a supplemental thing, something new to speed up art-making for all those times when all you need to do is add a quick shadow on a rock or a leaf or whatever, and you don't feel like adding 2 new layers to accomplish this.
A new faster kind of mask
Moderators: Víctor Paredes, Belgarath, slowtiger
Re: A new faster kind of mask
It might be an unpopular opinion but i think the whole Masking system should be overhauled. It's pretty unintuitive and confusing at the moment. I know how it works but it's quite a hassle at the moment to set anything up. This where i have to say a node-based workflow really shines because i can mask different things from each other which may not even be hierarchical next to each other. But something that works more like Clipping Masks etc. in Photoshop and that is represented visually in the layer view would be definitely a good addition instead of this "Add to Mask", "Subtract from Mask but keep invisible" "Multiply by Mask but keep somewhat visible except thursdays and sundays unless there's rain, then just delete completely" stuff 
Just my 2c.
Just my 2c.Re: A new faster kind of mask
The new Moho 14 feature "Liquid Shapes" accomplishes exactly what I desired when I made this feature suggestion.
The common way to make, for example, a leaf with a shadow and highlight involves masking and takes four layers: 1 group layer and 3 vector layers.
The Liquid Shapes method allows all three shapes to exist on the same vector layer. The "shadow" shape and the "highlight" shape are above the main shape, and both extend past the main shape, but only the overlapping portions are visible on the main shape. The result looks like you used a mask, but the process only takes 1 layer. You simply select the highlight and shadow shapes and click the CLIP button. BAM!
Thanks, Lost Marble!
The common way to make, for example, a leaf with a shadow and highlight involves masking and takes four layers: 1 group layer and 3 vector layers.
The Liquid Shapes method allows all three shapes to exist on the same vector layer. The "shadow" shape and the "highlight" shape are above the main shape, and both extend past the main shape, but only the overlapping portions are visible on the main shape. The result looks like you used a mask, but the process only takes 1 layer. You simply select the highlight and shadow shapes and click the CLIP button. BAM!
Thanks, Lost Marble!