Gtk settings are in ~/.gtkrc-2.0 file. Add this line there:
gtk-double-click-time = 500
where 500 is the maximum time between two clicks in milliseconds.
There doesn't seem to be any documentation of the gtk configuration file besides the property lists in the gtk API reference
, so it may be a good idea to post a short list of the most useful stuff that can be put in that file:
gtk-theme-name = "ThinIce"
# Display messagebox buttons in standard order (yes-no-cancel) instead the default backwards one.
gtk-alternative-button-order = 1
gtk-font-name = "Arial 10"
# Make combobox widgets look better.
# I believe there is one-line way to do this, but I haven't found it yet.
GtkComboBox::appears-as-list = 1
class "GtkComboBox" style "combobox_style"