Hello, welcome to the forum!
I am having difficulty in figuring exactly what the area/ size of the dashboard that will be visible to someone that logs directly into the dashboard will be?
If I understand you correctly, you are wondering what 'portion' of the available DGLux dashboard is shown in edit mode? If so, then the partial answer is that yes - in absolute layout mode it is 'cropped', and the dglux design environment will obscure part of your dashboard, if you do indeed have dashboard larger than the available layout preview window. A solution in this case may be to use the 'Application Scale' function under the 'Option' menu, which will allow you to design your dashboard at an arbitrary scale.
However, as you would probably imagine, it is best practice to create your dashboards so they are scalable to any browser size. In this case you can resize your browser window and the elements rearrange to fit.
I haven't quite mastered this myself but here is a link I found helpful:
If you follow the suggestions in the first reply in that thread, you'll get a dynamically scaling dashboard.
You can also see some best practice tips in this video, if you haven't seen it already: http://forum.infiniteautomation.com/forum/posts/list/1192.page
Is there a way of undocking this menu so I can have a better grasp of the entire screen that will be viewed. I am aware of the design mode/view mode function.
I don't think there's any way of disabling this menu, other than switching to View mode as you mentioned (If you save your dashboard as you go, you could always have the dashboard open fullscreen in another tab and reload it to check layout). As above the intended way of working with DGLux is such that the menu bar's presence shouldn't bother you.
Also upon logging in " http://localhost:8080/dglux/login.htm "Is there an option to add my own logo to this screen or this design fixed?
Is there a way to draw an object with the line tool, e.g. a cube, and hen fill this with a color I can bind properties to?
You can draw a shape using the polygon or bezier tools. Hover over the starting point until it turns green then click to end the shape, and it is automatically filled. If you select the shape then you can adjust the fill and effect properties in the right-hand side panes or drop values on to the properties to create bindings.
It would be very interesting to hear your thoughts on DGLux and Mango as compared to other commercial SCADA and HMI packages. I'm a beginner with Mango and DGLux but it's also the first such package I've used.