The code to determine whether the GTK library is available is now in Fl_X11_System_Driver::probe_for_GTK()
called both by Fl_Printer::begin_job() and Fl_Native_File_Chooser.
New Fl::option OPTION_PRINTER_USES_GTK allows to deactivate use of
the Gnome print dialog.
Minor change in Fl_Native_File_Chooser: GTK version 3 is searched before version 2,
whereas the search order was the opposite before.
Subject "Bug in 1.4 Displaying PNG under x64 Kernel x86 app." in fltk.general
contains a report by Darren Legge that presents the problem,
and a later post stating the code modification does fix the problem.
The case was under macOS with a non-GL parent window mapped to a retina display
containing a GL subwindow and if the app did not call Fl::use_high_res_GL(1).
Per-Monitor V2 awareness mode is supported on Windows 10 1703 or above
and has window title bars correctly scaled on HighDPI screens.
Before this commit, FLTK Windows apps were "Per-Monitor-V1 DPI Aware".
FLTK apps detect at run-time whether the V2 mode is possible.
The new argument gives the window to be captured, or NULL to indicate capture
from the current offscreen.
Calling this function becomes easier because less dependent on global variables.
Previously, each time fl_font(fnum, fsize) was called, functions
pango_font_description_free() and pango_font_description_from_string()
would be called.
Now, pango_font_description_from_string() is called only once, the first time
an Fl_Font is used.
Rename member function Fl_Surface_Device::end_current_() to end_current(),
set it protected, and make it called by the destructor of all classes
derived from Fl_Surface_Device that re-implement end_current().
This way, end_current() runs equally if Fl_Surface_Device()::pop_current()
is called before or after the drawing surface is deleted.
Under gnome, Tweaks -> Fonts ->Scaling factor allows to change
the size of all fonts handled by gnome.
With that change, FLTK apps obey to changes to Xft.dpi.
Previously, the display scaling factor value under gnome was sought in the gnome
database using the gnome_scale_factor() function. But that information is no
longer present.
File $HOME/.config/monitors.xml was also used to get that information.
Using the Xft.dpi X resource is simpler and more general because it's
effective both for gnome and KDE.
The procedure to set screen scaling factors becomes:
1) each screen scaling factor is set to 1
2) the OS is queried according to each platform to get screen scaling factor
values
3) The value of FLTK_SCALING_FACTOR, if present, is used to multiply
scaling factors
