Drawing tools on the diagram canvas always started new shapes and free
text from a fixed hardcoded default (Qt's plain QPen()/QBrush(), and
the static Preferences font) -- changing a shape's color or a text's
font had zero effect on what the next new item of that type got, even
within the same editing session.
Add LastUsedStyle: a small in-memory, session-scoped static helper
(no QSettings, no persistence across restarts -- this is a live "what
did I just use" value, not a new app-wide default). Write side hooks
capture the value right where the properties editors already apply a
change (ShapeGraphicsItemPropertiesWidget::associatedUndo(), both the
live-edit dock path and the modal editProperty() dialog path; and
IndiTextPropertiesWidget::on_m_font_pb_clicked() right after the font
dialog returns). Read side hooks apply the stored value, if any, to a
newly created item: DiagramEventAddShape::mousePressEvent for shapes,
IndependentTextItem's constructor for free text (falling back to the
existing QETApp::indiTextsItemFont() Preferences default otherwise).
Doesn't touch the element/symbol editor's own drawing tools (a
separate subsystem) or add last-used text color (no color control
exists in the text properties UI to originate it from yet).
ispyisail