Combining CharacterViewer with FontBook in Yosemite
The problem you mention has existed since OS X 10.7 was released nearly 4 years ago, so it has been discussed a lot in various places.  I think the best fix is probably to use the 3rd party alternative palette, Ultra Character Map.

https://itunes.apple.com/us/app/ultra-character-map/id520265986?mt=12

However if I remember right it cannot handle glyphs with no unicode codepoint assigned (i.e glyph variants).