Only apply cursor mode to focused windows.

src/input.c

@@ -52,6 +52,8 @@ static void setCursorMode(_GLFWwindow* window, int newMode)
     if (oldMode == newMode)
         return;
 
+    if (window == _glfw.focusedWindow)
+    {
         if (oldMode == GLFW_CURSOR_CAPTURED)
             _glfwPlatformSetCursorPos(window, _glfw.cursorPosX, _glfw.cursorPosY);
         else if (newMode == GLFW_CURSOR_CAPTURED)
@@ -66,6 +68,8 @@ static void setCursorMode(_GLFWwindow* window, int newMode)
         }
 
         _glfwPlatformSetCursorMode(window, newMode);
+    }
+
     window->cursorMode = newMode;
 }