Moving the editor's frame into math-editor.ui left `math_body` and `math_actions` as
<child> elements of the *window* rather than of `math_outer`, because those edits were
anchored on the file's tail and closed the outer box two elements early. A GtkWindow
takes exactly one default <child>, so nothing failed loudly: the body -- with the canvas
and the parameter form inside it -- was left parentless, visible but never mapped, 0x0,
drawing nothing. Two symptoms, one cause: the canvas is blank, and the window is sized
around the head row and the buttons alone.
Measured against the pre-move revision in a worktree, same probe, same environment:
before this fix `canvas=0x0 mapped=0 window=756x940`; after it `canvas=420x836 mapped=1
window=938x940`, which is the old revision's own reading exactly.
It survived because that slice's probe read the editor's *values* (nodes, gain, output,
name, unit) and nothing about its structure. Every other panel moved that day has a
structural reading -- `controls_inside=13/13`, `nested=1`, `labels=2 list=1` -- and none
of them was affected. `[math-probe] editor frame:` is that reading now: the canvas's
allocation, its mapped state, and whether the canvas and the name entry are inside the
dialog at all, delayed 500 ms because an allocation only exists after a layout. In the
broken build it read `0x0 mapped=0 in_dialog=0`.
check_ui passes both files: the XML was valid and every property type-checked.
Martino Ferrari
c3d588f03d