WaitProperty on styles?

Have you tried just simply

obj.WaitProperty("VisibleOnScreen", true, -1);

Note that the third parameter is the wait time in milliseconds.  -1 uses the default wait time in Project Properties Playback.

Now, if you need to specifically check a style setting... I don't know if this will help with the display one, but I use this for checking values of CSS styles applied to controls.

function getCSSProperty(element, prop){
     var style;
     style = Aliases.browser.Page('*').contentDocument.defaultView.getComputedStyle(element, '');
     return style.getPropertyValue(prop);
}

function checkCSSProperty(element, prop, checkValue){
    var testValue;
    testValue = getCSSProperty(element, prop);
    if (checkValue == testValue){
        Log.Checkpoint(prop + ' has value of ' + checkValue);
    } 
    else {
        Log.Error(prop + ' value of ' + testValue + ' does not match ' + checkValue);
    } 
} 

element is any onscreen object rendered by the web page.  So, I pass the element in to checkCSSProperty, the text string of the property, and the value I'm looking for.  When I run that piece of script, I get a verification of whether or not the CSS property matches the desired value.  It would look something like this:

function foo(){
    checkCSSProperty(Aliases.browser.myPage.myButton, 'background-color', 'rgb(153, 0, 0)')
}

If the color matches, I get a checkpoint logged with the green check mark.  If it doesn't, I get an error.

Perhaps this will help, too.