I'm assuming you man FX inserts, in which case you just got my vote sir. However, there is a reason for the double-click: currently the single click expands-collapses the FX slot, and double-click opens the actual plugin. Here's my proposed solution:
Double-click and single-click don't play well together, because to detect a single-click the program must wait a fixed amount of time before it can assume the user intended to issue a single-click. That's why, when you single-click an FX slot in S1, there is a short delay before it expands or collapses. This short delay is not a show-stopper but it is quite annoying nonetheless.
FX slots also respond to right-click. The right-click brings up a small context menu. Here's where I see room for improvement: this menu can also be opened via a left-click on the small down-arrow button, so one of the two methods can be considered redundant:
This is probably a good time to point out the elephant in the room: that the small arrow is too hard to notice against the similarly-colored background, which makes it even more redundant.
Expanding-collapsing of slots could instead be accomplished by means of a dedicated expand-collapse button on the slot, while the menu opens only via right-click. In addition, remove from the menu any redundant commands, for example, why would anyone want Expand/Collapse in this menu when you can already accomplish the same with a single click without opening the menu?
Here is a mock-up of my proposed solution, notice how the expand-collapse arrow button gets flipped upside-down when the fx slot is expanded, similar to the track expand-collapse button. I've also made the buttons a bit brighter because currently they are too hard to see.
I would get rid of the following right-click menu items:
Edit...: Single-left-click FX slot would do the same, so it's not needed.
Expand/Collapse: Single-left-click dedicated expand-collapse button on FX slot would do the same, so it's not needed.
Bypass: I wouldn't entirely get rid of this, but I would implement right-click on the actiavte-deactivate button () toggles bypass. Furthermore, bypassed slots should have a different background, because currently they look the same as non-bypassed slots, which is not very good. Something like this might work well: