GridLayout 
    GtkGridLayout is a layout manager which arranges child widgets in rows and columns.
Children have an "attach point" defined by the horizontal and vertical index of the cell they occupy; children can span multiple rows or columns. The layout properties for setting the attach points and spans are set using the class@Gtk.GridLayoutChild associated to each child widget.
The behaviour of GtkGridLayout when several children occupy the same grid cell is undefined.
GtkGridLayout can be used like a GtkBoxLayout if all children are attached to the same row or column; however, if you only ever need a single row or column, you should consider using GtkBoxLayout.
Constructors
Properties
The row to align to the baseline, when GtkWidget:valign is set to %GTK_ALIGN_BASELINE.
Whether all the columns in the grid have the same width.
The amount of space between to consecutive columns.
Whether all the rows in the grid have the same height.
The amount of space between to consecutive rows.
Functions
Assigns the given @width, @height, and @baseline to a @widget, and computes the position and sizes of the children of the @widget using the layout management policy of @manager.
Retrieves a GtkLayoutChild instance for the GtkLayoutManager, creating one if necessary.
Retrieves the request mode of @manager.
Returns the baseline position of @row.
Queues a resize on the GtkWidget using @manager, if any.
Sets how the baseline should be positioned on @row of the grid, in case that row is assigned more space than is requested.