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Windows

Tk applications are composed of one or more windows. Understanding how windows behave — and how they interact with focus, modality, and the event loop — is essential for building correct desktop applications with bootstack.

This page explains window behavior at a platform level and how bootstack expects windows to be used.

Root window

Every Tk application has exactly one root window.

In Tkinter, this window is created when the root application object is instantiated. All other windows exist within the context of this root.

The root window: - owns the Tcl/Tk interpreter - manages global state such as styles and images - serves as the parent for all other windows

bootstack formalizes this role through the App object. See Guides → App Structure for application organization patterns.

Top-level windows

Additional windows are created using toplevel windows.

Top-level windows: - are independent OS-level windows - have their own title, size, and decorations - share the same Tcl/Tk interpreter as the root

They are commonly used for: - dialogs - secondary views - floating tool panels

Window ownership

A toplevel window may be associated with a parent window.

Ownership affects: - window stacking - focus behavior - minimization and restoration

Associating dialogs with a parent window improves user experience and prevents windows from becoming lost behind others.

Modality

A modal window restricts user interaction until it is dismissed.

In Tk, modality is implemented through a combination of: - pointer and keyboard grabs - focus management - event waiting (wait_window, wait_visibility)

bootstack encourages explicit modal patterns rather than implicit blocking.

Window lifetime

Windows have an explicit lifetime:

  • created
  • displayed
  • hidden or destroyed

Destroying a window releases its resources. Hidden windows still consume resources and retain state.

bootstack favors explicit destruction when windows are no longer needed.

Focus and activation

Window focus determines where keyboard input is delivered.

Focus behavior depends on: - window activation state - platform window manager rules - explicit focus calls

Correct focus handling is especially important for dialogs and forms.

bootstack guidance on windows

bootstack promotes the following patterns:

  • use a single root window per application
  • associate dialogs with a parent window
  • prefer local grabs over global grabs
  • destroy windows explicitly when done

These patterns improve predictability and usability across platforms. See Widgets → Dialogs for pre-built dialog patterns.

Common pitfalls

  • creating multiple root windows
  • failing to set a dialog parent
  • relying on global grabs unnecessarily
  • leaking windows by hiding instead of destroying them

Understanding window behavior helps avoid these issues.

Next steps