1.7.3 is a bugfix update released on July 11, 2019 alongside a bugfix update for the Breaking Ground expansion.

Changes

Added same vessel part collisions advanced tweakable.
Adjusted KerbalEVA Action messages to be above center screen.
Made KerbalEVA screen position configurable via Gamesettings - EVA_SCREEN_MESSAGE_X,EVA_SCREEN_MESSAGE_Y
Add ability to switch secondary docking ports (docked) to primary via the PAW.
Add advanced tweakable to docking ports that allows the user to set the attraction force percentage as they are docking.
Convert same vessel docking connections to real docked connections whenever the vessel undocks or decouples elsewhere on the vessel.
Remove from symmetry functionality added to all parts.
Add capability for text entry on float fields in the Part Action Window.
Clear some references on returning to main menu to release memory.
Add ExternalCmdSeat Ejection Force (advanced tweakable).
Add Leave Seat KSPAction.

Fix Contracts using Greek alphabet from failing to display when game set to Russian Language.

Fix maneuver node tabs being interactable in flight mode even when tabs are hidden.
Fix temperature renderer messing with child part renderer parameters.
Fix EVA portrait when launching a vessel with Kerbal in external command seat.
Fix kerbal highlighting during mouse over.
Fix radiator panels not rotating properly.
Fix loss of axis and extended action group data when copying parts in the editor.
Fix assigned action/axis bindings not highlighting in action group editor when action sets are enabled.
Fix part positioning errors on vessel spawning far from Unity Origin.

Part class now has isVesselEVA property which handles when vessel is null.
Add ability to override default flow mode on ModuleResource.
Add activeEditor attribute to BaseAction to allow these to be disabled.
Add GameEvent onPartActionNumericSlider when Numeric Slider button is pressed on a PAW.
Add GameEvent onSceneConfirmExit, runs after user input to leave scene prior to FlightState saving.

References