If you select a plugin to install there is a install button but nothing happened. It is more plausible to install the selected plugin instead of doing nothing or check first a select box.
And also there is a remove button, but anyway if you click this you get query for restart, ok he does it, but NOTHING happened. Nice.
I have the same behaviour on my workplace machine, but not at gome. This can be traced, at least in my case, to a policy on the machine that prevents anything being launched as administrator. In particular, if N++ is installed outside the standard Program Files folder, PM thinks it needs to restart N++ as admin, and trouble starts there.
Dave is aware of the problem, and said he'd eventually fix it, without a timetable.
So, at work, I just don't use PM. At home, it works fine and automates a few things as advertised.