It will be. The test releases currently available on this website are technically proprietary, but that's only because I'm too busy to package the source code and pick the right license.
(If you mean free-of-cost or free-to-share, it already is.)
Vara aims to support non-artificial works, while still supporting a digital workflow. This is why many features like the shape tools, copy-paste, cloning and filters are avoided. If you need such features, there are applications like GIMP out there. But if there is a need to have them in Vara itself (maybe Vara feels simpler or faster), then Vara will be forked to have them. In any case, Vara itself will remain simple.
There is a feature matrix in the home page of Vara. Please check it out to know more about the features included, considered and omitted.
Make sure you are drawing with a pressure-sensitive graphics tablet instead of a mouse. It could be possible to mimic pressure-sensitivity based on mouse velocity or some other mouse-related paramter, but this is not implemented yet.
The pressure sensitivity of Vara is tested on Ubuntu/KDE Plasma with a Wacom CTL-472/K0-CX 6 inch graphics tablet. It cost less than Rs. 4,000, and for an entry-level model, its performance is extremely satisfactory. (Please note that this is not a sponsored advertisement; I'm just sharing info that could be useful.)
If you are using a graphics tablet and still don't get the expected result, please let me know.
Simply be clearing the background layer. To accomplish this, please select the background layer by pressing the BG button from the Layers group, and then press the Clear button from the Layer Actions group (or just press the Delete key in your keyboard, which stands for Edit > Clear).
WARNING: Please note that you have to do the above before you do any drawing on the background layer; otherwise all you've drawn on that layer will be gone.
Vara automatically makes the background layer white because that's what most beginners would want. Only advanced users will need a transparent background (because they wish to do further processing with the artwork using some other software, or want to include it in something like a website), and such users can always take an additional step to achieve the same.
The area filled by the Bucket Fill Tool has a ragged edge because Vara's brush strokes are very smooth and the additional pixels added for that smoothness (called anti-aliasing) makes it difficult for the fill algorithm to decide when to stop.
Unfortunately, you can't solve this problem by using the Fill Tool alone. But there is a solution. First, draw the bursh strokes on the FG layer and fill the area with the Fill Tool. Then switch to the BG layer and touch the edges manually using the brush tool (with the same colour used for filling). You can safely draw over the brush strokes that define the edges because those strokes are on the FG layer and you are now in the BG layer.
I'd like to add some feathering and edge detection to the fill algorithm, but that's of low priority since digital painting seems to depend more on painting with the brush rather than using the fill tool, because the former looks natural.