Double-clicking a placed element (or right-click > "Éditer l'élément")
opens its properties via Element::editProperty(), which constructs a
PropertiesEditorDialog with a real parent (QApplication::activeWindow()).
On macOS, a QDialog that has both a parent and Qt::WindowModal set falls
back to Cocoa's automatic sheet presentation. Reports (and this
codebase's own existing workarounds) indicate this can render stuck
centered on screen, non-draggable, with symmetric resize -- rather than
a proper attached, movable window -- unlike Linux/X11 where the same
dialog behaves as a normal draggable QDialog.
Two other dialogs in this codebase already explicitly opt into the
correct macOS sheet presentation for this exact reason:
ElementDialog::setUpWidget() and DiagramPropertiesDialog's setup both do
setWindowModality(Qt::WindowModal);
#ifdef Q_OS_MACOS
setWindowFlags(Qt::Sheet);
#endif
PropertiesEditorDialog -- used for editing Element, QetShapeItem, and
DiagramImageItem properties, all reached via double-click on a diagram
item -- had neither this opt-in nor an opt-out, so it likely fell into
the same automatic-sheet behavior but without the explicit flag,
matching the reported "stuck centered, can't drag" symptom.
Fix: apply the same setWindowModality()/Q_OS_MACOS Qt::Sheet pattern
already used by the other two dialogs, in PropertiesEditorDialog's
constructor -- fixing all three call sites (element, shape, and image
property editing) at once, since they share this one dialog class.
Verified: clean rebuild, all three call sites (element.cpp,
qetshapeitem.cpp, diagramimageitem.cpp) recompiled and linked
successfully with no errors or warnings.
Not verified: the actual reported symptom is macOS/Cocoa-specific
window presentation behavior, which cannot be reproduced or confirmed
fixed in this Linux/Xvfb sandbox -- no macOS environment is available
here. Confidence rests on the exact same fix pattern already being
established and presumably working for two other dialogs in this
codebase for the identical class of problem.
ispyisail