I IMPROVED CHAINWINDER Field of the Invention This invention relates to a chainwinder and in particular to an improved chainwinder for a window. Whilst the invention may be applied to opening or closing a range of articles 5 including skylights etc, for convenience sake it shall be described herein in terms of a chainwinder for opening and closing awning windows. Background to the Invention This invention relates to a window winder that uses a chain connected to a hinged window such that varying the length of the chain varies the degree of openness of the 0 window. The invention is particularly relevant to lockable window winders but is not limited to such. Generally, such mechanisms are used on windows, which are pivotally hinged at a top portion with the window winder being attached to the windowsill and a chain extending from and attached to a bottom portion of the window so that it is able to pivot outwards 5 around the top hinge. A particular important feature of lockable window winders is the security offered by such products. Windows are a clear entry point to premises and therefore like doors require locks to prevent unauthorised access. However unlike doors, windows generally need to be left partially open to allow fresh air to enter. Further due to the window not being the 20 usual 30 access when people leave premises the doors are locked but the windows are overlooked. It is therefore important to provide lockable chainwinders that increase security. There is already a substantial security element of lockable chainwinders in that it requires the key to lock in closed position or in partially open position which still prevents access, 5 35 while still allowing manual closing of window.
2 However a first particular security problem associated with window winders of this kind, is that often the drive handle is forced. This can allow the chain to be deformed from its usual track path and thereby forcibly engage the side of the casing. Over time this can cause undue wear and tear on the casing until the casing fails but solely this means or in 5 combination with other means such as weather conditions. Another security problem of operation of chainwinders is that the drive gear needs to have components of different precision and quality and strength. Having an integral lock does not allow this and raises the costs to the highest quality and highest precision for the whole item. Alternatively as is usual practice the lowest quality and lowest strength is 0 used and allows one or more sections of the drive gear to fail over continuous use or when undue force is applied. This makes a security issue in that the window could be readily opened. A further particular problem is that it is a requirement for a keylock to have a key to lock and unlock. However operation is unclear as keys have symmetrical heads and therefore 5 not clear if locked or unlocked in an upright or upside down position. Accordingly, it is an object of the present invention to overcome or at least substantially ameliorate one or more of the disadvantages of the prior art. Summary of the Invention In one form the invention provides a chainwinder including a housing formed by a 20 covering body and closed by an attachable base, the housing for receiving a chain therein and a drive means engageable with the chain to selectively drive the chain from the housing and alter the degree of openness of an attached window; wherein the chainwinder can be substantially assembled with improving security including any one or more of the following: 25 i. improvements in structure and assembly including construction in order to minimise bulging of chain within casing when drive gear force driven ii. Improvements in drive gear including better construction 3 iii. Improvements in key lock including providing identification of locked position which is clearly different to position of unlocked position. The invention in one form provides a chainwinder including a housing formed by a covering body and closed by an attachable base, the housing for receiving a chain therein 5 and a drive means engageable with the chain having a drive gear to selectively drive the chain from the housing and alter the degree of openness of an attached window; wherein the chainwinder includes an idler gear having a plurality of peripheral teeth that fit into the chain at the distal end of the chain from the end that extends out of the chain winder housing, the idler gear providing a turning arc for the end of the chain which is following 0 an arcuate path within the chain winder housing; wherein the idler gear having central formation to limit deflection or torsional deformation of the idler gear or deformation by the contact of the sprocket idler gear to the rest of the chainwinder such as bulging of chain within casing, when the drive gear is forcibly overdriven. The sprocket idler gear can have strengthening central formation on one or both sides of 5 the idler gear and extends out of the plane of the sprocket teeth in order to minimise deformation of the sprocket idler gear or deformation of the contact of the sprocket idler gear to the rest of the chainwinder such as bulging of chain within casing when the drive gear is forcibly overdriven. The sprocket idler gear can have central formation extending out of the plane of the z0 sprocket teeth in order to allow the idler gear to travel along longitudinal channel between the arcuate path of the chain and to engage a fixed portion of the chainwinder to stop the travel of the idler gear and thereby provide a short chain effect and the engagement of the central formation extending out of the plane with the chainwinder minimising deflection of the sprocket idler gear or deformation of the contact of the sprocket idler 25 gear to the rest of the chainwinder or bulging of chain within casing when the drive gear is forcibly overdriven. Preferably the central formation includes the idler gear having a collar on at least one side for engaging parts of the chainwinder on at least a respective upper or lower side relative to the plane of the plurality of peripheral teeth of the idler gear, wherein the idler gear is 30 able to move along the channel on the base plate within the casing when the chain is driven by the drive gear, the idler gear including a central collar in a plane alongside the 4 plane of the plurality of peripheral teeth that fit into the chain and the casing including a curved end stop such that the collar can engage the curved end stop so that as the idler gear is forced further the collar freely rotates and engages the curved end stop and substantially prevents any breakage or deformation or misalignment of the idler gear. 5 The central formation can include the sprocket idler gear having a protudable element mounted at or near the centre of the sprocket idler gear wherein the protrusion able to extend out of the plane of the sprocket teeth in order to allow the idler gear to travel along longitudinal channel between the arcuate path of the chain and to engage a fixed portion of the chainwinder to stop the travel of the idler gear to prevent further relative movement 0 of the idler gear in the chainwinder and thereby limit the length of chain able to extend out of the chainwinder to provide an alterable length chainwinder. Preferably the idler gear has central collar formations on at least one side around central mounting in order to minimise deformable torsion of the idler gear when sprockets engaging chain within casing when drive gear force driven. 5 Preferably the idler gear and casing having engaging formations in order to minimise bulging of chain within casing when drive gear force driven. The idler gear is able to move along the channel on the base plate within the casing when the chain is driven by the drive gear, the idler gear including a central collar in a plane alongside the plane of the plurality of peripheral teeth that fit into the chain and the casing 20 including a curved end stop such that the collar can engage the curved end stop so that as the idler gear is forced further the collar freely rotates and engages the curved end stop and substantially prevents any breakage or deformation or misalignment of the idler gear. The chainwinder can have the idler gear with a collar on at least one side for parts of the 25 chainwinder on at least a respective upper or lower side relative to the plane of the plurality of peripheral teeth of the idler gear. Preferably the chainwinder with the idler gear has a central means for receiving a protrusion that is able to engage a part of the chainwinder to prevent further relevant movement of the idler gear and thereby limit the length of chain able to extend out of the chainwinder to provide an alterable length chainwinder. The chainwinder can include at least one mounting element for mounting and fixing from outside the chainwinder without disassembling the base from the housing body. The at 5 least one mounting element can be a handle fittable to the drive means and lockable without disassembling the base from the housing body. The chainwinder can include at least one adjustment element for adjusting a function of the chainwinder and accessible from outside the chainwinder without disassembling the base from the housing body. The at least one adjustment element can be an element for o altering the effective length of chain able to be selectively driven from the housing to alter the degree of openness of an attached window. The present invention also provides a chainwinder formed by a subassembly and a covering housing, the chainwinder including a subassembly having a base in which is formed a channel for receiving a chain and further having a top at least partially overlying the base and chain therein and for 5 receiving and mounting a slide lock and a drive means engageable therewith wherein the chainwinder is substantially assembled with all parts and then covered by the housing whereby the base of the subassembly forms the base of the housing; and the chainwinder handle extends from outside the housing through the drive means and the subassembly to lock all the parts and to provide means for driving the chain into and out 0 of the housing. In a particular form of the chainwinder there is a window winder including: a housing for securing to a window ledge; a chain extending out of the housing and attachable to an openable window; a drive means having a rotatable handle external of the housing for varying the length of the chain extending out of the housing in order to vary the degree of 25 the opening of the window; and a locking means including a detent means associated with the drive means of the chain and preventing the chain from being further extended from the housing, wherein the locking means includes a key lock for effecting movement of the detent means between a lockable and an unlockable position and the ratchet gear is coaxial and adjacent the rotatable handle. 30 An improved chainwinder for improving security including any one or more of the following: 6 Improvements in structure and assembly including i. construction in order to minimise bulging of chain within casing when drive gear force driven ii. Improvements in drive gear including better construction 5 iii. Improvements in key lock including providing identification of locked position which is clearly different to position of unlocked position. It can be seen that in one form the invention achieves an aim of construction in order to minimise bulging of chain within casing when drive gear force driven by providing a strengthening collar. In another way the invention achieves the aim by the sprocket 0 idler gear having central formation extending out of the plane of the sprocket teeth in order to allow the idler gear to travel along longitudinal channel between the arcuate path of the chain and to engage a fixed portion of the chainwinder to stop the travel of the idler gear and thereby the engagement of the central formation extending out of the plane with the chainwinder minimising deflection of the sprocket idler gear or 5 deformation of the contact of the sprocket idler gear to the rest of the chainwinder or bulging of chain within casing when the drive gear is forcibly overdriven. Brief Description of the Drawings In order that the invention can be more readily understood embodiments will be described by way of non-limiting example with reference to the drawings wherein: 20 Figures 1 and 2 show a chainwinder of the invention in exploded view showing the housing placed over the subassembly with new improved security means; Figures 3 and 4 show photographic view of embodiment of Figures 1 and 2 showing chain extending around idler gear and protruding away from base showing one element of new improved security means of Figure 1; 25 Figures 5 and 6 are a top photographic view of embodiments of Figures 3 and 4 with chain removed to further show one element of new improved security means of Figure 1; Figures 7 to 12 are details of drive gear and handle attachable to drive gear forming further new improved security means of Figure 1; 7 Description of a Preferred Embodiment of the Invention In this preferred embodiment, and as shown in the exploded view of Figures 1 and 2 the invention provides a housing 12 of a chainwinder 11 with base 15 for securing to a window ledge. A chain 21 extends out of the housing 12 through opening 13 and 5 attachable to an openable window by attachment bracket 16 at the end of the chain 21. A drive means including a sprocket gear or chain gear 42 and a worm gear 43 are driven by a rotatable J handle 51 extending external of the housing 12 allowing the user to vary the length of the chain 21 extending out of the housing in order to vary the degree of the opening of the window. The chainwinder includes a locking means 61 0 including a detent means or lock slide associated with the drive means of the chain and preventing the chain from being further extended from the housing, wherein the locking means includes a key lock for effecting movement of the detent means between a lockable and an unlockable position and the ratchet gear or sprocket gear 42 is coaxial and adjacent the rotatable handle 51. 5 In order for the various details of the invention to be shown portions of the chainwinder 22 of figure 1 and 2 are shown in more detail in other Figures including the handle shown in Figures 8 to 10, the assembly structure including the idler gear at Figures 3 to 6. Other figures show the improved chain and the improved versatility of the chain to 0 form a short chain and to include the improved security features. Referring to Figure 2 there is shown the base 15 of the chainwinder 22 having a course for allowing a chain 21 to extend and protrude out an opening 13. A sprocket gear 42 is mounted in a metal bush in a receiving partially circular outer section of the base with a 25 central locating hole so that drive gear including the worm gear 43 can drive sprocket gear can drive the chain 21 out of the opening 13. The metal bush ensures stronger integrity and less wear. The end of the chain 21 has an attachment bracket 16 which can be fitted fixedly to the window by screws extending through screw holes. 30 The chainwinder is substantially assembled with all parts and then covered by the housing 12 whereby the base of the subassembly forms the base of the housing. The chainwinder handle 51 extends from outside the housing 12 through the drive means 43 and the subassembly and top subassembly and with the pin 59 engaging end of handle 8 51 to lock all the parts and to provide means for driving the chain into and out of the housing. A lock slide (not shown) is supported by the top of the subassembly and engages 5 between the separate ratchet 45 of the drive means and the key lock mounted in spaced opening 148 of the housing 12 such that turning the key to lock position prevents driving of the drive means and prevents further opening of the window. A handle 51 extends from outside the; housing 12 and extending substantially through opening 14A of the housing and the subassembly to be fixed in position by a locking 0 means 59 accessible from an outer side of the base 15 closing the bottom of the housing 12. A bush 47 and wafer washer spring or thrust washer 46 mount the drive gear including the worm gear 43 and separate ratchet 45 at one end while at the other end is provided 5 a flat surface 26 on the top subassembly 25. When mounted within the housing 12 the drive gear is aligned with the opening 14A in the housing 12 and is mounted to have flat surfaces at either end provided by the bush and wafer washer spring and the inner surface of the housing 12 at one end and the supporting flat surface 26 of the subassembly at the other end and in this way provide stable mounting of the worm gear 0 while minimising wear on the housing. A drive means is provided in the form of the handle 51 which has a spindle 53 and extends through the opening 14A of the housing 12 and further supports the worm gear therethrough. The idler gear 31 has a plurality of peripheral teeth 35 that fit into the end of the chain 21 at the distal end of the chain from the end of that extends out of the chain winder housing. The idler gear 31 provides a turning arc for the end of the chain which is following an arcuate path within the chain winder housing. 30 The idler gear 31 further has a central opening 32, which is able to receive a screw means 41 that extends and protrudes beyond the central opening 32. The screw means 41 protrudes through the base 15 that closes the bottom opening of the chain winder housing 16. Therefore the screw 41 will extend through the hole 18 in the base 15 and 9 engage into the threaded hole at the centre of the idler gear 31 which can fit within the arcuate portion of the chain 22. As shown in Figures 3 and 4 the idler gear is able to move along the channel on the 5 base plate within the casing (not shown) when the chain 21 is driven by the drive gear 42. However to avoid breakage or deformation or misalignment of the idler gear which would allow the chain to misalign and engage or bulge the casing the idler gear includes a central collar 34 in a plane alongside the plane of the plurality of peripheral teeth 35 that fit into the chain 21. This collar 34 can engage a curved end stop 17 so that as the o idler gear is forced further the collar freely rotates and engages the curved end stop 17 and substantially; prevents any breakage or deformation or misalignment of the idler gear. The movement of the idler gear 31 and engagement with the curved end stop 17 is further simulated without the chain in Figures 5 and 6. 5 Improvements in handle include folding handle, method for holding removable handle, and a handle extending from outside the housing and extending substantially through the housing and the subassembly to be fixed in position by a locking means accessible from an outer side of the housing. As shown in Figures 7 to 12 the handle 51 is configured with crank having a spindle 53 0 with a curved lower formation and the spindle and the curve formation can extend through the drive means including the separate worm gear 43 and ratchet 45. The top handle portion 51 is mounted to the crank in a folding manner by an elbow joint comprising a sleeve mounted on the crank intersecting with a sleeve holding the handle by a pivoting pin. A further spring mechanism locates two balls into a groove on the 25 inner surface of the handle knob, when the knob is in the operational position. This eliminates the likelihood of the knob being accidentally pulled up when the winder is being operated. When the knob is pulled up the spring mechanism will hold the knob in a position so it may be folded. 30 As shown in Figure 7 is the worm gear 43 while the ratchet 45 is shown in Figure 11 both from top view while they are both shown in side view in Figure 12. It can be seen that the worm gear has a solid worm external structure while the ratchet gear has a plurality of fine circumferential teeth. The separate structure allows for maximum strength and precision matching of manufacture dependent on the part. In particular the 10 teeth of the ratchet can be finely made and even with different stronger material so as to avoid chipping or shearing when the drive gear is forced. Mounting between the parts is further strengthened by the ratchet gear having central mounting shape that matches central mounting opening in the worm gear. 5 The handle 51 in location mounts the drive gear 43 within the housing 12 and with a locking pin extending from the base 15 to abut and thereby hold the curved lower formation and retain the handle 51 in a captured position and thereby lock the top elements of the chainwinder 22 to the base 15. 0 A further improvement in security includes Improvements in key lock including providing identification of locked position which is clearly different to position of unlocked position. In one form this is provided by the locking mechanism requiring only quarter turn in order to proceed from locked to unlocked. Therefore key in vertical position provides a 5 different indication to the key in the horizontal position and therefore clearly identifies difference between locked and unlocked. While we have described herein particular embodiments of a chainwinder. it is further envisaged that other embodiments of the invention could exhibit any number and 0 combination of any one of the features previously described. However, it is to be understood that any variations and modifications which can be made without departing from the spirit of the invention are included in the scope thereof as defined in the following claims.