is it possible to have transparent backgrounds to sliders? If so how can I do this please.

Many thanks!

no, the drawing instruction sent to the canvas has -fill #xxxxxx where xxxxxx is the color value in hex so it sends a color. in tk it would have to be -fill '' to be transparent, so there's no way to do this from pd

but some somehow I have a slider that I've shaped to be the size of a table array with a wavefile inside it and I can see both the slider bar and the audio?

@Fauveboy The arrays are "transparent" but the slider is actually white (by default).

@Fauveboy You will have to use an [hslider] under (behind) the array.
It will need to auto-size to the canvas size of the array.

The array needs to be a sub-patch with "graph on parent" so that it shows on the main patch with the hslider behind it, but because it is not actually "there" you can grab the hslider through it........ AND..... which is more complicated..... created after the hslider so that it is actually on top.....

The cursor (slider bar) will not be on top, but it will show through the white space of the array........ which fortunately is transparent where there are no data points shown..... and if you make the cursor a different colour...... red for example... it will be very visible and useable.
David.
PS it is done in this patch, but it is Pd extended..... so....... but the bits are in there.....waaaav.zip .... messages to the cursor to follow audio playback and control it etc.
Just found a vanilla version that I never finished, but will be "more" working in vanilla so easier to follow........waaav vanilla not working.zip