It requires a precise mouse down button in the rectangle border bounds
to select a full table, so it has added a tolerance value.

Change-Id: Ia8213ae452f93cd2faa957a50246638d1eb2198e
Reviewed-on: https://gerrit.libreoffice.org/27356Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Henry Castro <hcastro@collabora.com>