frame 20 the slide 49 travels outwardly toward one end of the t track 51 to enable this closing movement of the operator link 41 simultaneously as the slide 49 travels to its position of fig4 the toggle formed by pivot link 56 and stabilizer link 61 is flattened out until these two links are in a near dead center relationship fig4 relative to their pivots 54 and 63 and lie roughly parallel to the operator link 41 and slide 49 during this collapsing of the operating linkage from the position of fig3 to the position of fig4 the casement window is swung from a partly open or full open position to a closed position as this movement takes place the depending locking tongue 67 on extension plate 42 nearest the slot 43 and pivot 63 gradually moves into contact with the outermost opposing raised locking projection 65 of stabilizer link 61 this contact occurs near the end of travel of the two links 41 and 61 toward their positions of fig4 and hence the locking tongue 67 will help to force the stabilizer link home to the window closing position and will also positively lock the window operating linkage in its collapsed position of fig4 so that the window cannot be pried.