Yes, we remember about it.

If i receive more requests about light browser, i will add such option.

Unfortunately i cannot make a big preview, the browser is a system controller.

We will improve that soon, at least in Lasso Fill

Any idea how to reproduce that?

After researches - i think i know how to do it, but it needs a lot of changes, so it must wait, sorry...

It is ok, it works the same in other image editing applications.

It happens because selection edge pixels are semi-transparent.
Let's say the pixel opacity is 50%. Now when you paint, you fill layer pixel with only 50%, so layer pixel opacity is 50% after making a stroke.
Then you erase the selection-edge pixes,but you erase only "50%" of alpha (because selection pixel opacity is 50%), so the layer pixels opacity goes down from 50% to 25%.

I will try to fix it asap.

I think everything is ok. The result is different because
- in Reference mode you use Layer 1, Layer 2 and Layer 3 and current drawing buffer (empty before you start a stroke) as a source for Smudge
- in Current And Below mode you use Layer 1, Layer 2, Layer 3 and Layer 4 (which is also drawing buffer, not empty before you start a stroke) as a source

If you want to achieve the same result in both cases you have to add Layer 4 to the list of reference layers.