GimpChainButton Widget to visually connect two entry widgets. This widget provides a button showing either a linked or a broken chain that can be used to link two entries, spinbuttons, colors or other GUI elements and show that they may be locked. Use it for example to connect X and Y ratios to provide the possibility of a constrained aspect ratio. The #GimpChainButton only gives visual feedback, it does not really connect widgets. You have to take care of locking the values yourself by checking the state of the #GimpChainButton whenever a value changes in one of the connected widgets and adjusting the other value if necessary. You may want to use the convenience function gimp_coordinates_new() to set up two GimpSizeEntries (see #GimpSizeEntry) linked with a #GimpChainButton. Checks if the passed pointer is a pointer to a #GimpChainButton and performs the cast if valid. @obj: The pointer to cast. @GIMP_CHAIN_TOP: Use if the GimpChainButton is used attached to the top of the widgets it connects. @GIMP_CHAIN_LEFT: Use if the GimpChainButton is used attached to the left of the widgets it connects. @GIMP_CHAIN_BOTTOM: Use if the GimpChainButton is used attached to the bottom of the widgets it connects. @GIMP_CHAIN_RIGHT: Use if the GimpChainButton is used attached to the right of the widgets it connects. @position: @Returns: @gcb: @is_active: @gcb: @Returns: