Layout with pack, grid, and place

Simply creating a widget with button .b -text OK allocates it in memory and registers it in the widget tree, but it will not appear on screen until you hand it to a geometry manager—pack, grid, or place—which is responsible for calculating its actual size and position within its parent. Each geometry manager implements a completely different layout algorithm: pack stacks widgets against the edges of their container in the order they're packed, grid arranges widgets into a table of rows and columns, and place positions a widget at explicit coordinates or fractions of its parent's size. Tk enforces that a single container can only use one geometry manager for its direct children at a time—mixing pack and grid calls on widgets that share the same parent produces a well-known deadlock error—but nothing stops you from using pack inside one frame and grid inside a sibling frame nested within it.

pack positions each widget against one side of its parent—-side top, bottom, left, or right—and widgets are placed in the order the pack command is called, each claiming space and shrinking the remaining area available to the next one. The -fill option (x, y, or both) lets a widget stretch to fill the space it's been allocated in a given direction, while -expand yes tells the widget to claim any extra leftover space in the parent when the window is resized. -padx and -pady add external spacing between the widget and its neighbors, and -ipadx/-ipady add internal padding inside the widget itself. Because pack is order-sensitive, swapping the order of two pack calls for widgets on the same side can visibly rearrange the layout even though every option stayed identical.

grid arranges widgets into an invisible table using -row and -column, with -rowspan and -columnspan letting a widget stretch across multiple cells the way a merged cell does in a spreadsheet. The -sticky option controls how a widget behaves when its cell is larger than its natural size, using compass directions like nsew to stretch it in all four directions, w to left-align it, or ns to stretch it vertically only. Unlike pack, grid rows and columns don't automatically grow with the window; you must explicitly tell a row or column to absorb extra space with grid rowconfigure . 0 -weight 1 or grid columnconfigure . 1 -weight 2, where the weight value determines the proportion of extra space that row or column receives relative to others with nonzero weight.

place is the most primitive of the three managers: it positions a widget using absolute pixel coordinates (-x 20 -y 40) or coordinates relative to the parent's size (-relx 0.5 -rely 0.5 -anchor center), and optionally sizes it as a fraction of the parent with -relwidth/-relheight. Because place ignores the natural layout flow entirely, it's the right tool for a small set of specific cases—overlaying a splash-screen logo in the exact center of a window, drawing a status badge in a fixed corner of a canvas-like frame, or building a custom drag-and-drop surface—but it should not be used for ordinary form layout, since widgets placed with fixed coordinates don't reflow sensibly when the window is resized the way pack and grid do.