config.allowedContent = true
because CKEditor by default tries to filter many types of content. It does this not always but after some actions, that's why you lose the map after going from Source to WYSIWYG mode: this is one of such actions.
config.doksoft_image_preview_runtimes = 'html5,flash,html4,silverlight,gears';
The first of all HTML5 runtime will be loaded, so you do not need to change any config after updating. But if you want you can shuffle this priority list as you want, but note that only Flash and HTML5 were tested enough and can be recommended. All others are a bit specific in any case.
Strange, your demo http://doksoft.com/soft/ckeditor-image-preview-upload/demo.html runs but doesn't show the progression as your Quick File Upload.(http://doksoft.com/soft/ckeditor-file-upload/demo.html).
Is it possible to active upload progression for this image plugin too ?
More, I have problem with the 'Add File' button' on my project : It doesn't upload files. No error. Just close. Only drag & drop completely runs (close, upload, and tag in CKEditor text).
I use your last ASP.Net dll and plugins versions.
Best Regards,
HB