Windows 64 bit - invalidate doesnt?

If I take a 32bit Windows app to my 64 bit Windows 10 Home Dell laptop, it works.
If I compile the same code to 64bit and deploy to the same machine, invalidate calls just don’t seem to cause things to redraw - only actual Refresh calls.
Xojo 2018 R3

Is this a known issue?

which interval you call invalidate? maybe to often?

(How can there be a ‘too often’? … the OS is supposed to aggregate the calls and do one refresh when it can, isnt it…?)

32 bit same code same app works fine. 64 not at all.

Theoretical yes, practical not.
Just try what happens if you invalidate by button click.
If you always say its invalidate maybe its never drawn. Some mouse events came often.

What do you invalidate? A window? ContainerControl? Canvas?

I have a canvas, on which I draw rectangles or other shapes, as the mouse is moved around with the button held down.
It invalidates a rectangular area around where the mouse has been.
If I dont invalidate (on 32bit), the effects of the drawing are not seen until the mouse is released.
On 64 bit, that is what happens even if I do invalidate.

I dont think anyone else is using 64 bit for interactive graphics in this way.
Its not ‘just’ a screen with a couple of buttons and a list box… all those components work fine.
In many ways, its more like a game.

Are you able to replicate it in a simple demo project that you can upload here?

Me had a project some month ago.
I use always 64bit in my projects.
Cant remember how i solved it, must look into this project.

This morning I have managed (after years of trying) to get Xojo 2015R3.1 to compile for 64bit
(I had to increase the memory to 16Gb and the processors to 2 instead of one, it used 10Gb while working, and took nearly an hour)

But at the end of that, it seems that the code works when compiled with 2015, but not with 2018 or later.
Pointing an accusatory finger at the changes to graphics which occurred after 2015.

I’ll give it a try

this project with shapes drawing works in 2020r2 in 64 bit.
i believe the issue with invalidate i had in a rotary knob control where controls was overlapping then i changed it into a single component.

That reminds me . To even get to this point, I had to redesign some custom controls that used a containercontrol … nothing was being drawn at all. I had to take the controls out and make them non-overlapping children of the main window…

if you still have a problem a demo project would help as julian mentioned.