Warnings and the devtools
At the end of this chapter, you can see what your app is doing.
Turn it on
kui_native::app("Todo").devtools(true).run(Todo::default())Or set KUI_DEVTOOLS=1 and run any app. A panel opens beside the app,
docked to the right. Ctrl+Shift+D moves it (left, right, bottom, its
own window, off); Ctrl+Shift+I moves the keyboard into it and back.
Three tabs
facts — what the runtime believes right now: the theme and where it came from, the window and its size, the focused node, the modifier keys, the node count, and a latency graph.
events — every event handed to your on_event, as it arrives: the
frame number, the node it came from, and the payload as data. Click a
row to unfold the payload. This is the tab to keep open while you
learn. When a button does nothing, look here first: either the click
arrived and your handler ignored it, or it never arrived and the button
is not where you think it is.
tree — the last frame’s nodes, foldable, with a filter. Click a
node to see its box, its layout, its paint, its handlers and its state.
The picker (Ctrl+Shift+P, or the crosshair button) selects a node by
pointing at it.
Warnings
A mistake that fails silently in most UI libraries comes back as data
in kui: a warning with a stable code, the node it is about, and a
sentence that says what to do. They show in the events tab, and a test
reads them with d.warnings().
The ones you will meet first:
| code | what happened | what to do |
|---|---|---|
control-without-name | a button, editor or checkbox with no text inside it and no label | give it .label("..") |
duplicate-key | two nodes in one frame share a key | key rows by id, not by text that repeats |
transition-auto-key | a node with a transition sits among siblings that change count, under a position key | give it with_keyed or with_indexed |
modal-behind-content | a modal float declared before the content that paints over it | declare the modal last |
grow-weight-ignored | Sizing::Grow(2.0) on the only grow child | it has nothing to split against; use grow_width() |
item-outside-container | a radio with no radio_group above it | wrap the items |
exit-budget | one frame removed more than 4096 nodes declaring exit | that removal did not animate; remove a parent instead of its children |
The full list is the Warnings table in
docs/props.md. Each
(code, node) pair is reported once, so a warning in a view that runs
every frame does not flood the log.
Where this is decided
- The panel is drawn by the core, not by the window runner, so a Node,
Lua or C app gets the same one, and
KUI_DEVTOOLS=1works for all of them. - Your app can add a tab of its own:
features/devtools_tab.rs.