I should have mentioned this earlier, the background color is mainly made for toasts/alerts
however, as Kodular is extended builder the background color works for some of the dialogs as well, you can either look at the docs or by hovering above the block to find out on which you can apply the background color..
e.g. docs
Custom Choose Dialog
Shows a dialog box with two buttons, from which the user can choose. If cancelable is true there will be an additional CANCEL button. Pressing a button will raise the GotCustomChooseDialog event. The “choice” parameter to GotCustomChooseDialog will be the text on the button that was pressed, or “Cancel” if the CANCEL button was pressed. You can use the “Light Theme” property to have a light or dark background. Or you enable “Use Background Color” property to use the background color property as background dialog color. Use the ‘Show Custom Dialog’ block to the show the created custom dialog. The added component must be visible on screen. After you used this block here it will be removed automatic from screen and will be only visible again after you have shown the custom dialog.
e.g. block
So if you are using an block that doesn’t specify/mention this
Or you enable “Use Background Color” property to use the background color property as background dialog color.
either in docs or by hovering on it, then it’s unfortunately not available for it..
Edit: Also you have to build to APK to see it..