Adjust a workaround for versions before 3.22 when setting the font for
a control.
GTK+ version 3.22 starts paying attention to whether a font size for a
control is absolute (as opposed to being in points), so the workaround
that was put in place for earlier versions breaks.
In addition, some part of the drawing stack seems to round point sizes
to an integeral size after DPI conversion. Take that rounding into
account when setting the font size in `normal-control-font`.
Closes#1522
Allocation rules:
* Use `as-gtk-allocation' when creating a Gtk widget that is the main
container for a given window<%> object. When the resulting
reference becomes unreachable, the widget will be released with
gtk_widget_destroy() through a finalizer.
* Use `atomically' to create and attach a sub-widget within the main
widget. Don't use gtk_widget_destroy(); the containing widget will
destroy the enclosing widget.
* For temporary objects, use `atomically' to wrap both the allocation
and release.
Every call to a function whose name contains "new" needs to be in one
of those cases.
5e70534b43