Bugtracker #323: crash changing a label's color, but only when
confirmed via Enter -- clicking the dialog's own OK button with the
mouse doesn't crash. Reported on Windows 11 and Debian, with
"QObject::installEventFilter(): Cannot filter events for objects in
a different thread" immediately before the segfault.
Root cause: DynamicTextItemDelegate::createEditor()'s color case
constructed a QColorDialog and returned it directly as the item
view's editor widget for the color cell -- unlike every other case
in this same function, which returns a small inline widget
(QSpinBox, QComboBox, or, for the adjacent font case, a plain
placeholder). A QColorDialog is not designed to be used this way: it
is not one of the objectNames this delegate's own eventFilter()
special-cases, so Enter is handled by the base
QStyledItemDelegate::eventFilter() as an ordinary "commit and
destroy this small editor" trigger -- racing the dialog's own
internal OK-button accept/close path, which on Windows can hand off
to the native color picker. Clicking OK with the mouse doesn't go
through the same key-press path, which is why only Enter crashed.
Verified structurally: an embedded QColorDialog editor is a *child*
widget of the view's viewport rather than a proper top-level dialog
(confirmed with a standalone Qt program driving the real delegate
through QAbstractItemView::edit() -- searching QApplication's
top-level widgets never found it, only a search of the viewport's
children did), which is the same "used as something it isn't"
pattern, just observed a different way.
Fix: mirror the font case immediately above -- resolve the color via
the static, blocking QColorDialog::getColor() inside createEditor(),
and hand back a plain QWidget with the result stashed in two
properties (mirroring the font case's "ok" property) for
setModelData() to read. By the time the view processes any commit
trigger, the "editor" is an inert placeholder with no dialog state
left to race.
Verified end-to-end with the same standalone program: creates the
model item, triggers editing, finds the real (top-level, this time)
QColorDialog, clicks its actual OK button, confirms the color lands
on the placeholder's properties, sends the editor a synthetic Enter
keypress (the exact trigger from the bug report), and confirms the
final committed value in the model matches the picked color. Also
confirmed a full Release build (333/333) with no new warnings.
ispyisail
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