White patches around Custom Button

i am having a screen on which i have painted a image as a background and i am placing 6开发者_JAVA技巧 custom buttons in a verticalfield manager, every thing is working fine , but when focus comes on the last custom button, then it is surrounded by a white patch.. i don't no what the problem is...

Thanks in advance

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The following fix usually works for that white background around custom fields. Override the moveFocus method to do the following:

protected int moveFocus(int amount, int status, int time) {
    int val = super.moveFocus(amount, status, time);
    invalidate();
    return val;
}