Inserts a row or column at the specified position.
The new row or column is placed next to sibling, on the side
determined by side. If side is GTK_POS_TOP or GTK_POS_BOTTOM,
a row is inserted. If side is GTK_POS_LEFT of GTK_POS_RIGHT,
a column is inserted.
Inserts a row or column at the specified position. The new row or column is placed next to sibling, on the side determined by side. If side is GTK_POS_TOP or GTK_POS_BOTTOM, a row is inserted. If side is GTK_POS_LEFT of GTK_POS_RIGHT, a column is inserted.