Swiping form using SwipeBacksupport turns entire screen white - codenameone

Question

While swiping a form, the growing left part of the screen is just white until the swiping is done, when the "back-to" form finally is painted. Is this by design? I expected the "back-to" form either to be gradually revealed, or to slide in from the left.
On iOS and Android, the form being swiped also seems to turn white, so the whole screen is white until the swiping is over. This is not the case with the simulator, however, where you can see the form until it's swiped all the way out.
Code to reproduce the behaviour:
Form redForm = new Form("Red Form");
redForm.getAllStyles().setBgColor(0xff0000);
Button btnToBlueForm = new Button("Go to blue form");
redForm.add(btnToBlueForm);
Form blueForm = new Form("Blue Form");
blueForm.getAllStyles().setBgColor(0x0000ff);
LazyValue<Form> lazyRedForm = (Object... args) -> redForm;
SwipeBackSupport.bindBack(blueForm, lazyRedForm);
btnToBlueForm.addActionListener((ActionListener<ActionEvent>) (ActionEvent evt) -> {
blueForm.show();
SwipeBackSupport.bindBack(blueForm, lazyRedForm);
});
redForm.show();
Press the button in the red form. The blue form now appears. Swipe back and observe the effects.

Answer 1

That's because of the SlideFade mode in the transition. If you switch it to Slide it should work as expected with the background. Here's a version of your code that works as you would expect by applying the style to the content pane:
Form redForm = new Form("Red Form");
redForm.getContentPane().getAllStyles().setBgColor(0xff0000);
redForm.getContentPane().getAllStyles().setBgTransparency(255);
Button btnToBlueForm = new Button("Go to blue form");
redForm.add(btnToBlueForm);
Form blueForm = new Form("Blue Form");
blueForm.getContentPane().getAllStyles().setBgColor(0x0000ff);
blueForm.getContentPane().getAllStyles().setBgTransparency(255);
LazyValue<Form> lazyRedForm = (Object... args) -> redForm;
SwipeBackSupport.bindBack(blueForm, lazyRedForm);
btnToBlueForm.addActionListener((ActionListener<ActionEvent>) (ActionEvent evt) -> {
blueForm.show();
SwipeBackSupport.bindBack(blueForm, lazyRedForm);
});
redForm.show();
The reason this works as opposed to the original code is that SlideFade is two separate transitions one moving/fading the title and the other sliding the content pane alone. Since the content pane is transparent the background isn't painted as we assume it's the form background. By setting the content pane color/opacity we get the exact same effect at a layer the SlideFade will "see".