#2987 Default font settings don't work well with high DPI

[Sergei Golovan]

Hi!

As far as I can see the default font sizes on Unix are specified in pixels:

% font configure TkDefaultFont
-family sans-serif -size -12 -weight normal -slant roman -underline 0 -overstrike 0

As a result, they look too small on a high resolution screen (tried on a laptop with 165DPI display).