Dual or multiple monitors - one app full screen on monitor A - why can I not use the minimize buttons on monitor B

Hi Apple and community,

What are ways, if any, to not be limited by Apple's screen / monitor limitations?

I know it is possible, as I have experienced it using Matrox's solutions such as TripleHead2Go and there are probably others, but how do I do this:

• open some youtube video on monitor A
• go fullscreen on that video you just opened / started playing
• then => on monitor B, the window minimise buttons are greyed out?

On a side note:

Supose you have multiple monitors with really thin or no edges at all, why would you impose a limit to having an application partly span another monitor? There are numerous applications e.g. investing applications where you can arrange your "view" just the way you want by various ways of moving "information panes" to about any position within that view.

Suppose you have two or three 27" (rimless) monitors why limit e.g. having application A to span 1.3 monitors and having application B span only 1/3 of the second monitor?

Thanks for any pointer or way to remove these limitations!