Sorry, me again. After fiddling around I found out why it didn't work: because \placecontent was within the subject that it had to print. Kind of a Gordian Knot or what was it called...?
I modified my code a little, so that it looks better, but still one thing is missing... That's what my code looks like now:

%D I copied the head settings to "title", so that it has the same style as the rest
%D "title" will not be counted for TOC:

\setuphead[title][style=\ssbfc, color=foreground:contrast, alternative=middle]

\starttext

\setvariables
...

\startstandardmakeup %D else the content is placed at the very top, ignoring the header... (bad)

  \title{Table of contents}
  \vfill
  \placecontent
  \vfill
  
\stopstandardmakeup
    
\startslide[title={First Slide}]
...

Yet the one thing I am missing is that the TOC is not in the middle of the page.
I read some time ago that \vfill  has no effect at the very beginning or the very end of a page. A suggestion was to place a "ghost box" or something like that at the end or top respectively of the document. Yet I can't finde the article anymore. Can anybody provide some help with this or is there maybe a more elegant way to solve the whole TOC situation?

Greetings, Sebastian

2017-05-12 22:16 GMT+02:00 cryo shock <axteffekt@gmail.com>:
I forgot to add that I also tried a modified \setuplist:

\setuplist[subject][width=2cm,margin=2cm]
and
\setuplist[subject][margin=2cm]

I also added the following line to the component:

\setupcombinedlist[content][list={chapter,subject,subsubject,section,subsection,slide}]

Yet the Toc page stays blank...

2017-05-12 22:08 GMT+02:00 cryo shock <axteffekt@gmail.com>:
Hi guys, I downloaded a sample presentation with component and example presentation from a link off of ctxwiki. I will attach both files and a premade PDF that shows what I mean.

So far I edited the component a little in display style, yet I don't know why I can't get a simple table of content on the second slide.

In the component I found the following code:

\definehead
    [slide]
    [subject]
    [
      style=\ssbfc,
      color=foreground:contrast,
      alternative=middle,
      page=yes
    ]

So I understand that the head called slide comes from the head subject, which by default isn't shown in the table of content. So I searched ctxwiki for table of content and modified the above setup to

\definehead
    [slide]
    [subject]  % default: subject
    [
      style=\ssbfc,
      color=foreground:contrast,
      alternative=middle,
      page=yes,
      incrementnumber=yes,  % keep track of the number
      number=no             % but don't show it
    ]

I also added the following line:

\setuplist[subject][width=2cm]

The example .tex then starts with

\starttext

\setvariables
...
\startslide
...
\stopslide
...
\stoptext

So I inserted another \startslide \stopslide with \placecontent in between:

\startslide[title={T.o.c.}]
  \placecontent
\stopslide

Yet the rendered PDF shows only a blank page where the TOC is supposed to be.

Can anybody tell me what I am doing wrong?
Thanks in advance,

Sebastian