To center the virtual tour, you can use the feature of "anchor" in Tourweaver 4.00. In MainWindow, select the check box before Width and Height, if you set 100% for both width and height, the mainwindow will appear as 100% of the browser dimension:
Then you you can set anchors to all other components in the mainwindow, for example, go to properties of sceneviewer and select the checkbox before Width and Height, and then select the position of the sceneviewer you would like it to be in the mainwindow. I selected center:
In my test tour, I also used images above the sceneviewer be a fake skin. Because the sceneviewer is anchored, I have added four images with large width(1650) or height(1650), and set them all anchored to the right position:
Then the loading window is also anchored to the center:
In this way, no matter what dimension the browser is, the tour can always fill the whole window (I set width and height as 100%).
The published tour:
Did you check the two boxes before 'Width' and 'Height' in properties panel of sceneviewer? If so, please uncheck those two boxes and publish your tour. Then you can edit your tour html to add the code of <center>, and in this way the tour will be centered.