Pouring liquids in lines (or even choosing amount amount instead of dump all)

It’d be nice if we could choose how much liquid we want to pour out of a container, or even use a trail of flammable liquid to make a long “fuse” to things we want to blow up/set on fire. It would certainly make building fire traps more convenient if you could just set up a line of gas and set it on fire to draw enemies in.

In both the current stable (0.G) and - unless something majorly changed since my last look about a month ago - experimental versions this can already be done.

Open the [d]rop menu (or the [D]irectional drop + choose direction), go to the liquid (NOT the container it’s in; you might need to show the content of the container with > first), enter the number of “charges” of the liquid you wish to drop and press [Right-Arrow-Key] (or whatever key you’ve assigned the “Mark/unmark selected item” action to).
Now just confirm the selection with [Enter] and confirm that you want to drop a liquid.

This can also be done in current stable/experimental version, although not “by hand”.

You could build a (foldable) vehicle consisting only of a “wire” or any other cheap frame and a “leaky” tank (any tank that has less than 50% of it’s health left if I remember it right - the lower the remaining health, the faster it will empty out).
Fill it with a flammable liquid and drag it behind yourself to leave a trail of puddles. Wait with [5] or [.] between each movement to make sure that there will be no gaps.

yeah basically what i’m asking for is to be able to do this by hand without using technical work arounds

As written, you can do this by hand and the normal drop menu.

I agree, it should be easier. When unloading liquid maybe a menu pops up that lets you imput a number, that you would want to drop.

Extra inputs for no reason goes against the design philosophy. If you want to drop 100 charges you are going to have to type “100” regardless, there is no need to bother players with a popup (especially when 99.9% of the time they are not going to be dropping anything but the whole stack).