If Dolphin crashes, changes that have been made to settings are often
lost. This has been a minor annoyance for me when developing, but it has
become a much bigger issue recently due to the problem where Dolphin
freezes on shutdown for ROG Ally users.
Instead of saving the config when certain arbitrary settings are
changed, let's save the config when the user closes the settings window.
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.
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.
Reduces the amount of dependencies dragged in by the main window's
header. This also removes MainWindow.h includes elsewhere where they
aren't necessary, reducing the amount of UI files that need to be
recompiled if the main window's header changes.