!openmenu == para is parsed as (!openmenu) == para, so it first negates openmenu and then checks whether it is equal to para, which is most likely not what you want to do. You could write !(openmenu == para) which would mean the same thing as openmenu != para.

!a == b inverts a's value. For example if it's true, using ! will invert it to false.

if(!true == false) equals to if(false == false) which results as true.

but if(a != b) compares values, lets say a is true and b is false, so if(true == false) => false values are not the same. :)

In this case, if a==null and b==false so !a = true.

Then !a == b is false but a!=b is true. I hope that answer is helpful to you.