Unity 3D just shows orange square when resizing window. And since I'm not native english speaker, here is a screenshot showing what I'm trying to explain:
I can't really answer your question in terms of why there's a difference, but I can tell you how to change the Unity 3D settings to give you your "real time" redraws.
The 'Normal' setting is the one you want, giving you real time updates of the window during resize. On my machine though this is painfully slow.
The Rectangle and Outline are very similar and draw a box representing the resized window.
Personally I like the 'Stretch' option, which gives you a faked-update of the window contents by simply stretching them.
Hope that helps.
Are you meaning that Unity 3D does not reupdate the windows when you resize it, instead showing orange box as outline?
The answer is to save computer resource, since if you let otherwise it would be extremely slow, as windows need to be redrawed each time you resize it, and updating them in real time will make the program to redraw over and over again, resulting in extreme (not excessive) resource consumption.
Resizing windows while redrawing the whole content used to be smooth in Ubuntu. It stopped with Ubuntu 11.04 and Unity 3D on my computer which may be almost 5 years old but still no slouch. I believe it coincides with introduction of v0.9 of Compiz. Since then the "Normal" option for the "Resize Window" CCSM plugin is unusable. It is still broken in 12.04. Tonight I installed Xubuntu 12.04 in a VM and was astonished to see that windows are redrawn smoothly when resized! And we're talking virtual machine here (with 3D accel enabled).
Clearly, there is a serious problem with Compiz in that regard.
Edit: After a search I found the bug on Launchpad. Apparently a fix has been commited for 0.9.8 but I don't know if it will appear in 12.04. The bug can be found here on launchpad.
@ Linux Distance, with modern PCs saving computer resource is ridiculous, plenty of cycles to spare - and your answer is beside the point. This was working well for years. How about a real, useful answer instead of an opinion.