force height to round up to the nearest integer. fixes a bug where firefox was drawing sortable tracks elements with a non-integer height
force height to round up to the nearest integer. fixes a bug where firefox was drawing sortable tracks elements with a non-integer height

Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-webcode,Ensembl/ensembl-draw,Ensembl/ensembl-webcode