This commit allows compiling LyX with Qt6 when using autotools.
For a successful compilation the following 2 conditions must be met.
1) The Qt6 qmake has to come first in PATH, so that the command
"qmake -v | grep -o 'Qt version .'" returns "Qt version 6".
2) The --enable-qt6 switch has to be passed to the configure command.
If --enable-qt6 is used but Qt6 is not found, Qt5 is tried as a fallback.
If also Qt5 is not found, configuring for Qt4 is attempted.
If --enable-qt6 is not used, then things go as usual. This means that Qt5
is tried first and then Qt4, unless --disable-qt5 is used, in which case
Qt4 is directly attempted. This means that existing scripts should
continue working unmodified.
LyX should compile with Qt6 on windows and linux, and possibly also on
mac, but I could not test that. However, it is not guaranteed that it
works as it should. In particular I am not sure that I got right the
conversion from QRegExp to QRegularExpression. For sure, the syntax
highlighting seems to not work right. Someone in the know should take
a look at that. I am able to load documents and compile them but some
thourough testing is needed. However, when compiling for Qt5 or Qt4,
I tried to make sure that the functionality is preserved.
Some lfuns are handled directly in GuiApplication while handling
of menu hiding in fullscreen was done on the level of GuiView.
We'll see if this code movement breaks in different scenarios,
but quick grep suggested that the only other way to guiview
dispatch is through drag&drop when menu isn't involved.
Add a new ForceAll update flag that forces to update metrics and
redraw all buffer views.
The situation in multi windows setting is very fragile and will need
to be adressed properly in the 2.5 cycle.
Mistakes are visible but word replacement is disabled. Disable relevant
widgets depending on the situation.
Move updateView code to SpellcheckerWidget::Private.
To do this, hard-coded test for xcb had to be replaced with a call to
platformName(). Since this method does not exist in Qt4, we emulate
it.
Note that Qt5 uses xcb bindings for X11 system, while Qt4 relies on
older X11 bindings. We return platorm == "qt4x11" in this case.
Fixes bug #11746.
The method horizontalAdvance() replaces width() starting with Qt 5.11.
To handle this, all direct calls to QFontMetrics::width() are replaced
by calls to GuiFontMetrics::width(), and the code for
GuiFontMetrics::width(QChar) uses horizontalAdvance on newer Qt
versions.
