1.18.3 Can you answer these questions?

Can you answer these?

1.18.3.1 fill opacity, opacity, and draw opacity commands don't work at all - tikz, tikz3dplot

http://tex.stackexchange.com/questions/278715/fill-opacity-opacity-and-draw-opacity-commands-dont-work-at-all-tikz-tikz3

I'm new to tex.stackexchenge. I tried for many and many times to draw the circular shaded areas in red and orange in such a way to superimpose them in transparency (with an opacity parameter of 0.3)  ...
 

- asked by El BrontolA~\262n 2votes

1.18.3.2 Biber can't call method "get_field" on an undefined value

http://tex.stackexchange.com/questions/278305/biber-cant-call-method-get-field-on-an-undefined-value

Is this a bug, has the behaviour changed (i.e. it is a new 'feature') or is the end user simply an idiot? 
When I try to run Biber on code which compiled just fine until quite recently (i.e. prior to  ...
 

- asked by cfr 5votes

1.18.3.3 Draw an intersection of two planes

http://tex.stackexchange.com/questions/278709/draw-an-intersection-of-two-planes

I use this code for producing the intersection of two planes: 
\begin{figure}[h!] 
\centering 
% Generat amb TikZ 
\begin{tikzpicture}[x={(240:0.8cm)}, y={(-10:1cm)}, z={(0,1cm)}, 
...
 

- asked by somenxavier 2votes

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