Fix a regression in the previous release causing an error when setting background_opacity to zero

Fixes #7483

docs/changelog.rst

@@ -57,6 +57,8 @@ Detailed list of changes
 
 - Fix a regression in the previous release that caused horizontal scrolling via touchpad in fullscreen applications to be reversed on non-Wayland platforms (:iss:`7475`, :iss:`7481`)
 
+- Fix a regression in the previous release causing an error when setting background_opacity to zero (:iss:`7483`)
+
 
 0.35.0 [2024-05-25]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

kitty/boss.py

@@ -1325,7 +1325,7 @@ class Boss:
                 tm.resize()
 
     def _set_os_window_background_opacity(self, os_window_id: int, opacity: float) -> None:
-        change_background_opacity(os_window_id, max(0.1, min(opacity, 1.0)))
+        change_background_opacity(os_window_id, max(0.0, min(opacity, 1.0)))
 
     @ac('win', '''
         Set the background opacity for the active OS Window

kitty/rc/set_background_opacity.py

@@ -67,7 +67,7 @@ equal to the specified value, otherwise it will be set to the specified value.
             raise OpacityError('You must turn on the dynamic_background_opacity option in kitty.conf to be able to set background opacity')
         windows = self.windows_for_payload(boss, window, payload_get)
         for os_window_id in {w.os_window_id for w in windows if w}:
-            val: float = payload_get('opacity')
+            val: float = payload_get('opacity') or 0.
             if payload_get('toggle'):
                 current = background_opacity_of(os_window_id)
                 if current == val: