@joaqimb
I have viewed your Boogieboy and Namur galleries in Internet Explorer 11 and I do not see a flickering image and the Button Bar appears at the upper-right corner of the expanded gallery. Everything appears to be working as expected.
If these are not the galleries you are referring to, then please post the URL to the gallery in question and let me know what version of Internet Explorer you use.
The following are general tips which may help with the symptoms you describe but if the galleries I named above are the ones you are referring to, then the problem may be local to your computer or the version of Internet Explorer that you use.
I have the same problem in Internet Explorer. But not in Firefox or Google Chrome.
First of all, please ensure that you are using the latest version of Juicebox-Pro (v1.4.2).
Instructions for upgrading can be found here.
Please see this FAQ, which may help: My gallery looks strange in Internet Explorer 9. Why?
Also, please make sure that your Internet Explorer browser is not displaying your web page in Compatibility View.
Next, check your web page for any HTML errors. You can check the code on your web page with the W3C Markup Validation Service and then fix any errors reported. Once the code on your web page validates correctly, your web page should be rendered with greater predictability and consistency across different browsers.
And for more: when I go to full screen in IE, I loose my buttonbar at the top of the window.
Try one (or more) of the following:
Try setting a fully opaque expandedBackgroundColor (such as expandedBackgroundColor="rgba(255,255,255,1)") in JuiceboxBuilder-Pro's 'Customize -> Color' section (set the 'Opacity' value to '1').
Try setting expandInNewPage="TRUE" in JuiceboxBuilder-Pro's 'Customize -> General' section.
Try changing the useFullscreenExpand configuration option (from TRUE to FALSE or vice versa) in JuiceboxBuilder-Pro's 'Customize -> Lite' section.