Active Window –

Definition:
The active window is the currently focused window in a graphical user interface (GUI). It’s the window that receives input from the keyboard and mouse.

Key Characteristics:

1. Input Focus:
   Only one window can be active at a time. All keyboard input (and often most mouse interactions) are directed to this window.
2. Visual Indicators:
   • Most operating systems visually distinguish the active window, commonly by changing the title bar color or highlighting its border.
   • Inactive windows are usually dimmed or have grayed-out title bars.
3. Z-Order Position:
   The active window typically appears at the top of the Z-order, meaning it’s the foremost window in the stack of overlapping windows.
4. Switching Active Windows:
   • Users can switch between windows using shortcuts like Alt + Tab (Windows/Linux) or Command + Tab (macOS).
   • Clicking on a window with the mouse also brings it to the front and makes it active.
5. System Behaviour:
   • Operating systems manage the active window to ensure only one is receiving input.
   • Background tasks or windows may still run processes, but they don’t receive user input unless they are brought to the foreground.

Use Cases and Importance:

• User Experience: Helps users know where their actions are going—critical for typing, issuing commands, or interacting with applications.
• Security: Prevents unintended input going to a background application (e.g., entering a password into the wrong window).
• Multitasking: Makes it easier to manage multiple open applications by clearly indicating the focused one.