Add: WidgetDimensions for 'sparse' widget windows.

These are for windows that have space between widgets instead of being clumped together.

src/widget.cpp

@@ -152,9 +152,12 @@ const WidgetDimensions WidgetDimensions::unscaled = {
 	{WD_DROPDOWNTEXT_LEFT, WD_DROPDOWNTEXT_TOP, WD_DROPDOWNTEXT_RIGHT, WD_DROPDOWNTEXT_BOTTOM}, ///< dropdowntext
 	{20, 10, 20, 10},    ///< modalpopup
 	{3, 3, 3, 3},        ///< picker
+	{10, 8, 10, 8},      ///< sparse window padding
+	{10, 8, 10, 1},      ///< resizable sparse window padding
 	1,                   ///< pressed
 	1,                   ///< vsep_picker
 	WD_PAR_VSEP_NORMAL,  ///< vsep_normal
+	4,                   ///< vsep_sparse
 	WD_PAR_VSEP_WIDE,    ///< vsep_wide
 	2,                   ///< hsep_normal
 	6,                   ///< hsep_wide

src/window_gui.h

@@ -51,10 +51,13 @@ struct WidgetDimensions {
 	RectPadding dropdowntext; ///< Offsets of text within a dropdown widget.
 	RectPadding modalpopup;   ///< Padding for a modal popup.
 	RectPadding picker;       ///< Padding for a picker (dock, station, etc) window.
+	RectPadding sparse;       ///< Padding used for 'sparse' widget window, usually containing multiple frames.
+	RectPadding sparse_resize; ///< Padding used for a resizeable 'sparse' widget window, usually containing multiple frames.
 
 	int pressed;              ///< Offset for contents of depressed widget.
 	int vsep_picker;          ///< Vertical spacing of picker-window widgets.
 	int vsep_normal;          ///< Normal vertical spacing.
+	int vsep_sparse;          ///< Normal vertical spacing for 'sparse' widget window.
 	int vsep_wide;            ///< Wide vertical spacing.
 	int hsep_normal;          ///< Normal horizontal spacing.
 	int hsep_wide;            ///< Wide horizontal spacing.