Fixes glyphs not updating when loading between fonts at the same
index. Fixes GlyphEditor spinbox inadvertently modifying width
of last selected index.
Adds cut, copy, paste and delete to GlyphEditor. Font preview has
moved to a separate resizable ToolWindow. Font metadata can now be
hidden. FontEditor and glyph widgets can now be re-initialized
instead of resetting window's main widget after loading new fonts.
We have both the normal menu items and keyboard shortcuts for these by
now. No need to have always-visible buttons -- makes the app more
consistent with the other apps, and makes it use up less vertical space.
