You can organize your forms and form collections into subwindows that can be resizable and detachable. In the Main Window node, if you change the Main window type to Subwindows, the lower part of the Main Window Editor becomes a workspace for the layout of subwindows.

Note that the New Form Wizard templates Basic, Subwindows, sections, and graphics; and Subwindows, tabs, and graphics will create applications containing subwindows.

The Window Layout section is visible if the Main window type is set to Subwindows.

Working with subwindows is similar to working with forms in grid mode. You can insert columns to the left and to the right of existing columns. Rows can also be added above and below existing rows, and rows and columns can be deleted. Grid cells can be merged and then split again. On the ribbon of the Main Window Editor, there is a Rows & Columns button that enables you to quickly create a layout with a specified number of rows and columns.

The sizes of the rows and columns can be specified interactively by dragging. They can also be specified manually in the Window Layout section, in the Settings window of the Main Window.

The column width and row height settings are not interpreted as absolute width and height, but rather summed together, and each individual row and column size is then interpreted as a fraction of the total size. A percentage value is displayed in the column and row headers in the Subwindows layout area.

The Allow dragging between subwindows setting controls whether forms can be dragged and moved between the different parts of the subwindow area.

The Show form header in subwindows with a single form setting controls whether to the forms, which are alone in a subwindow, should have a header. This setting is only available when dragging between subwindows is disabled.

Only one type of object can be placed in each of the grid cells used to define the window layout. This is called a subwindow object and is automatically added to a grid cell as soon as it is created. The Settings window for a subwindow object is shown in the figure below.

This Settings window makes it possible to set which forms that are open in different subwindows. In the table below the model tree in the Forms section, you can specify if the form is Initially open in the subwindow, if it is Closeable, and if it is Vertically scrollable. A form that is Closeable will have a cross icon in the window title for closing it.

Since a form can only be shown in one subwindow, the Forms section, containing the available forms, is filtered to only show forms that have not yet been added to a subwindow. Also, the Forms section only shows global forms and not local forms.

When starting an application, each form that has been added to the Forms section, and where the checkbox in the Initially open column is selected, is shown in the corresponding subwindow. The Title of the form is used as the title on the corresponding tab.

The Default form setting specifies which form is initially active in the subwindow when launching the application.