Description:
Zip containing a Writer document and 6 images
Setting (c.s.s.awt.XAnimatedImages) StepTime does not change the rate of images display, at least on Windows 10.
Attachment is a zip containing AnimatedProblems.odt and 6 png images. Unzip all in the same folder. Click the button to run the macro BASIC and open the dialog with animation.
StepTime should be 2000ms between two images.

Steps to Reproduce:
1.Setting (c.s.s.awt.XAnimatedImages) StepTime does not change the rate of images display.
2.Attachment is a zip containing AnimatedProblems.odt and 6 png images. Unzip all in the same folder. 
Run the macro : StepTime should be 2000ms between two images.


Actual Results:
StepTime seems to be 100ms

Expected Results:
StepTime should be 2000ms 


Reproducible: Always


User Profile Reset: No



Additional Info:
It turns out that the control peer actually calls the respective VCL class (Throbber) to change the step time:

AnimatedImagesPeer::setProperty()

case BASEPROPERTY_STEP_TIME:
{
    sal_Int32 nStepTime( 0 );
    if ( i_value >>= nStepTime )
         pThrobber->setStepTime( nStepTime );
    break;
}

Unfortunately, Throbber::setStepTime() simply stores that value in a member variable 

void  setStepTime( sal_Int32 nStepTime )  { mnStepTime = nStepTime; }

that member variable is never used to actually set the AutoTimer timeout: the timeout is only set on the Throbber constructor, where the timeout value is set to a default value of 100:

Throbber::Throbber( Window* i_parentWindow, WinBits i_style, const ImageSet i_imageSet )
    :ImageControl( i_parentWindow, i_style )
    ,mbRepeat( sal_True )
    ,mnStepTime( 100 )
    ,mnCurStep( 0 )
    ,mnStepCount( 0 )
    ,meImageSet( i_imageSet )
{
    maWaitTimer.SetTimeout( mnStepTime );
    maWaitTimer.SetTimeoutHdl( LINK( this, Throbber, TimeOutHdl ) );

    SetScaleMode( ImageScaleMode::None );
    initImages();
}

Possible solutions:

a) make Throbber::setStepTime() update the AutoTimer's timeout, but what if the Throbber is running (== the timer is active)?
b) reset the AutoTimer's timeout in Throbber::start(), that is, when the animation is started; this will have the effect that setting the step time while the animation is running will only take effect after it restarts
c) ....

solution to be tested : 
in the file vcl/source/control/throbber.cxx  change the start method like this: 
void Throbber::start()
{
    maWaitTimer.SetTimeout( mnStepTime );
    maWaitTimer.Start();
}