Keyword search with unbound identifier clears visualization

[bestchai]

Searching for something like "bam=foo" displays an appropriate error: "Unbound identifier: bam"

However, next, the visualization is cleared entirely. To get the view back, the search must be cleared.

Instead, the search box needs to be highlighted (to indicate error), but the visualization should remain.

[Issue created by bestchai: 2015-08-10]