[Pkg-tcltk-devel] Good way to (not) express TCL version dep in d/control ?

[Antti J=?iso-8859-1?B?5A==?=rvinen]

Dear Debian TCL Sirs,

suppose there is program depending on tcl/tk but it is not very picky about
its version - say, any 8.x release should do and hopefully future
versions too -> is there any preferred method of writing d/control?

I see there are (pseudo)packages tcl-dev and tk-dev (I need both) so
to-day I'm getting tcl8.6-dev+tk8.6-dev. What worries me is situation where
someone builds and has tcl8.6 and then tk development files from some
very old tk versions, say, it seems it is possible
to install both 8.5 and 8.6 development packages in parallel -> is
there way or need to force specific tk version to be used together
with tcl version. If I only say "tcl-dev,tk-dev" in dependencies of
the source package and don't specify any version numbers, this is not
going to happen? 

Another related question is that in configure script (or in my case, a
Qt .pro file) it seems like I need to figure out tcl version and add
-I/usr/include/tcl8.6 into CFLAGS or otherwise #include <tk.h> will fail in
finding <tcl.h> -> is there any well-mannered example about how to
detect the "best" tcl version? /usr/bin/tclsh might be symlinked to
some outrageously different version but naturally asking tclsh for
$tcl_version is my best bet also regarding development files
version. Or is it?

--
Antti, in avoidance of future d/control modifications