Resizing multiwin

[KenDown]

This may be teaching my grandmother to suck eggs, but I have discovered that you cannot resize a multiwin window. Or, at least, you can resize it, but usefully only make it smaller.

If you create a multiwin and then use SYS"SetWindowPos" to make it larger, you will naturally do VDU26. However you will be left with a black stripe at bottom or side (or both) which cannot be cleared with CLS or CLG. The graphics ORIGIN will be within that stripe (if you have made the window taller) but nothing drawn down there will appear. Even using VDU23,22 to create a larger MODE does not alter things.

The only solution is to create your multiwin at the maximum size, then make it smaller and, when necessary, restore it to the larger size, both using SYS"SetWindowPos".

I may be wrong, but my guess is that each window has a bitmap associated with it and all drawing or printing takes place on the bitmap and it is the bitmap that you see. When you use SYS"SetWindowPos" on a multiwin window that bitmap is not changed, which is why you get the black stripe impervious to drawing or printing.

Or perhaps there is something obvious of which I am ignorant, in which case enlightenment would be much appreciated.

[DDRM]

You are right, creating a new window involves creating a bitmap, which is of the width and height specified, so enlarging the window beyond that will have nothing to show. Creating the window as big as you want it would seem a sensible approach, but I guess you could create a larger bitmap later, and select it into the relevant device context, if you needed to?

Best wishes,

D