That’s a good feature request. Currently the Tooltip cannot be customized.
Would a global colour for all Tooltips work? That is how JUCE implements it, the colour is with the TooltipWindow. To have a bespoke colour per component would be a bit trickier to implement and probably involve a bespoke Tooltip class.
I have to ask what do you mean the Tooltip only shows over the slider?
You mean it should exclude the TextBox? I am not sure if that would be the right fix. The Tooltip usually applies to the slider and the textual input. The Slider is a special case, it could be argued to have a different text for the TextBox, is that what you mean?
For the ComboBox: the reason is a problem that was only recently fixed in JUCE: the PopupMenu of the ComboBox uses the colours from the LookAndFeel. But the LookAndFeels are shared in PGM, so that wouldn’t work.
To make it work you need new LookAndFeels, it works in the shipped “FoleysFinest” LookAndFeel, at least the text colours. I just realise the background seems broken. I will have a look asap.
I should probably add the same fix to the original juce LookAndFeel_Vx as well.