Allows easier conversion of legacy libraries.
Note that performance will be suboptimal as it must read/write each
library once for each symbol in the library. Doing otherwise would
require modifying the PlugIn API, which probably isn't worth it for
a one-time migration.
A note to developers, please do not set the minimum and/or size of bitmap
buttons. It causes bitmaps to get clipped using GTK on Linux. If the
bitmap button size is not acceptable, then supply an appropriately sized
bitmap rather than attempt to force the wxWidgets sizing mechanism to do
what you want. This almost always causes platform differences that do
not work well.