The button has multiple actions:
What is the corresponding value to enter in a condition:
Oh, indeed, we should add a selector in this condition as well 
I’ve created a feature request, I’ll add it here: Dans la condition "Condition sur variables", afficher les valeurs possibles lors d'un capteur avec constantes
In the meantime, here are the codes for each type of click:
"1": "Single click",
"2": "Double click",
"3": "Long click press",
"4": "Long click release",
"5": "Click held",
"6": "Long click",
"7": "On",
"8": "Off",
"9": "Decrease brightness",
"10": "Increase brightness",
"11": "Stop brightness",
"12": "Left arrow click",
"13": "Right arrow click",
"14": "Left arrow held",
"15": "Right arrow held",
"16": "Left arrow released",
"17": "Right arrow released",
"18": "Triple click",
"19": "Quadruple click",
"20": "Click released",
"21": "Lots of clicks",
"22": "Cube shaken",
"23": "Cube thrown",
"24": "Cube woken up",
"25": "Cube falls",
"26": "Cube tapped",
"27": "Cube slide",
"28": "Cube flip 180°",
"29": "Cube flip 90°",
"30": "Cube rotate left",
"31": "Cube rotate right",
"32": "Vibration",
"33": "Tilt",
"34": "Movements",
"35": "Emergency",
"36": "Disarm alarm",
"37": "Arm day zones",
"38": "Arm alarm",
"39": "On button pressed",
"40": "On button held",
"41": "Plus button pressed",
"42": "Plus button held",
"43": "Minus button pressed",
"44": "Minus button held",
"45": "Off button pressed",
"46": "Off button held",
"47": "Single press",
"48": "Long press",
"49": "Short release",
"50": "Long release",
"51": "Double press",
"52": "Toggle button",
"53": "Toggle button held",
"54": "Brightness Plus Click",
"55": "Brightness Plus Held",
"56": "Brightness Plus Released",
"57": "Brightness Minus Click",
"58": "Brightness Minus Held",
"59": "Brightness Minus Released",
"60": "Pressed",
"61": "Single Left",
"62": "Single Right",
"63": "Single on both",
"64": "Double Left",
"65": "Double Right",
"66": "Double on both",
"67": "Triple Left",
"68": "Triple Right",
"69": "Triple on both",
"70": "Held Left",
"71": "Held Right",
"72": "Held on both",
"73": "Single click Plus",
"74": "Single click Center",
"75": "Single click Minus",
"76": "Double click Plus",
"77": "Double click Center",
"78": "Double click Minus",
"79": "Held Plus",
"80": "Held Center",
"81": "Held Minus",
"82": "Released Plus",
"83": "Released Center",
"84": "Released Minus",
"85": "On double click",
"86": "Off double click",
"87": "Arm night zones",
"88": "Exit delay",
"89": "Button 1 single click",
"90": "Button 1 double click",
"91": "Button 1 long click",
"92": "Button 1 triple click",
"93": "Button 2 single click",
"94": "Button 2 double click",
"95": "Button 2 long click",
"96": "Button 2 triple click",
"97": "Button 3 single click",
"98": "Button 3 double click",
"99": "Button 3 long click",
"100": "Button 3 triple click",
"101": "Button 4 single click",
"102": "Button 4 double click",
"103": "Button 4 long click",
"104": "Button 4 triple click"
Oh yes indeed, I couldn’t have guessed! Thanks for the list
Now that I know what values this button can take (On=7 Off=8 Double-click On=85 Double-click Off=86 Increase Brightness=10 Decrease Brightness=9 Stop Brightness=11), I can’t figure out how to create the corresponding scene: it’s for controlling a light. I’m really clueless!!!