I have been trying to get to support for some time now. I have questions about what to do with GND+ pins in EPM7128slc84-15 devices. What happens if the pins are left open.

OK, I checked the .pin output file for my design (happens to use the exact same part) in QuartusII 13.0sp1. Here is the relevant comment:

---------------------------------------------------------------------------------
 -- NC            : No Connect. This pin has no internal connection to the device.
 -- DNU           : Do Not Use. This pin MUST NOT be connected.
 -- VCC           : Dedicated power pin, which MUST be connected to VCC.
 -- VCCIO         : Dedicated power pin, which MUST be connected to VCC
 --                 of its bank.
 -- GND           : Dedicated ground pin. Dedicated GND pins MUST be connected to GND.
 --					It can also be used to report unused dedicated pins. The connection
 --					on the board for unused dedicated pins depends on whether this will
 --					be used in a future design. One example is device migration. When
 --					using device migration, refer to the device pin-tables. If it is a
 --					GND pin in the pin table or if it will not be used in a future design
 --					for another purpose the it MUST be connected to GND. If it is an unused
 --					dedicated pin, then it can be connected to a valid signal on the board
 --					(low, high, or toggling) if that signal is required for a different
 --					revision of the design.
 -- GND+          : Unused input pin. It can also be used to report unused dual-purpose pins.
 --					This pin should be connected to GND. It may also be connected  to a
 --					valid signal  on the board  (low, high, or toggling)  if that signal
 --					is required for a different revision of the design.
 -- GND*          : Unused  I/O  pin. Connect each pin marked GND* directly to GND
 --           	    or leave it unconnected.
 -- RESERVED      : Unused I/O pin, which MUST be left unconnected.
 -- RESERVED_INPUT    : Pin is tri-stated and should be connected to the board.
 -- RESERVED_INPUT_WITH_WEAK_PULLUP    : Pin is tri-stated with internal weak pull-up resistor.
 -- RESERVED_INPUT_WITH_BUS_HOLD       : Pin is tri-stated with bus-hold circuitry.
 -- RESERVED_OUTPUT_DRIVEN_HIGH        : Pin is output driven high.
 -- NON_MIGRATABLE: This pin cannot be migrated.
 ---------------------------------------------------------------------------------
 

So GND+ is just an unused input pin. On that device in that package I see no pins flagged as GND+ or GND* in my .pin listing (I use all the I/Os available).