Remove window hints clearing the flag Qt::WindowContextHelpButtonHint,
which is already off by default in Qt 6.
In Qt 5 this flag was set by default for QDialogs, and on Windows put a
? button in the corner of the title bar allowing users to activate Qt's
QWhatsThis help system for a given widget. Since we don't set that text
the ? button was useless and so we hid it manually.
Previously, if you have "Hotkeys Require Window Focus" disabled, you could repeatedly use the "Open" hotkey, for example, to stack File Open windows over top of each other over and over.
This commit allows the hotkey manager to disable/enable on QFileDialog creation and destruction.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.