calculate the residuum
declare a lot of stuff ignorable so that i'm not overwhelmed by compiler messages and can figure out why something doesn't compile
the residual looks worse when i assume a size of 227 px diameter for the fiber
this fit does certainly not work very well.
a button click now immediatly causes the canvas to redraw
writing out the single-float fields array takes 107s
  107.321 seconds of real time
  0.840000 seconds of total run time (0.036000 user, 0.804000 system)
  0.78% CPU
  256,927,085,276 processor cycles
  867,024 bytes consed
looks like i can reimport the fields data
figure out how to modify the gui while the program is running: gtk-widget-destroy
store the widget and not only the adjustments in *adjustments*
it should actually suffice to just store the widgets. the adjustments are available using gtk methods
correct code to handle stored widgets from *adjustments*
only ft is shown in the vbox. i have to export the hbox instead of the spin button

 XPOS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
YPOS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
RADIUS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
KXPOS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
KYPOS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
KRADIUS

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
RB-FT
RB-FIT

(sbcl:1961): Gtk-CRITICAL **: gtk_box_pack: assertion 'gtk_widget_get_parent (child) == NULL' failed
this is confusing. perhaps i should introduce my own class to represent buttons and checkboxes
perhaps i don't need a class, just a few functions to extract widgets and adjustments from *adjustments*
simpler way to get values from the gui
one typo prevented check buttons from working
removing gui widgets works. but when trying to put them back in they obviously stay deleted. i will have to create them from scratch.
i can now add arbitrary check boxes to the running gtk window