EditCondition specific does not prevent values from being changed.

1) Using the Meta specifier EditCondition will gray out the property box so that it cannot be clicked, but using tab from another property box will place the cursor inside the grayed out box.
2) Values entered this way will be accepted when Enter is pressed rather than resetting back to the default value.

NOTE:
Only custom uses of EditCondition are affected by both conditions. Engine uses of the specifier (such as MassInKg of the Cube component) are subject to 1) but are not affected by 2) (changing MassInKg value while grayed out will return to default value).

Regression:
No - behavior exists for binary 4.14.3 as well

1. Open UE4 Editor (any project)
2. Add code to project based on Actor (MyActor)
3. Add the following to MyActor.h

   	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = test)
   		bool CustomCheckbox;
   
   	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = test, meta = (EditCondition = "!CustomCheckbox"))
   	float EditWhenTrue;
   

4. Compile
5. Create blueprint based on MyActor (MyActorBP)
6. Set CustomCheckbox to false - doing so will make "Edit when True" uneditable
7. Immediately after clicking checkbox, press Tab

Result:
After pressing Tab, the mouse cursor will be inside the Edit when True field and setting a value here will be accepted on enter even though the field is uneditable.

Expected:
When the field is grayed out, the value cannot be altered from its default value and the field cannot be entered with Tab.