the question is, if i create a custom shader network for my sprites is there a way to visualize that in the viewport??

it's easy to setup a sprites shader to render with mantra,
but the problem is that i want to be able to see the output in the viewport, for example if i create a vopsurface inside which i have some network.
in the render i can see my material on my sprites, but not in the viewport. i tried many approaches and couldn't do it, it always shows the color set in the color pop, while if i add a texture in the opengl tab i can see it on my sprites, but if i set the color in the opengl tab (without adding texture) ntg changes and the colors are those of the color pop.
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is it possible to see the shaders in the viewport for objects? what i mean by that is , if for example i attach a checkerboard material or a constant material with a texture to a grid, can i see it directly in the viewport?
because by default i can only see a gray material with some white specs on it, even though if i switch to shader view or i region render i can see the checkerboard or the texture i'm using.
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why when i try to use the enable xray for selected objects it doesn't work ? does it need a special treatment or smtg ?

waiting for your answers
Regards