Xfce - can't change window buttons' order in the panel like in Gnome
 

Is there anything I'm missing? Very ordinary action and seems that there's no such thing in Xfce. Can you do it?

Very simple. Just open the window manager settings and drag the buttons to rearrange.

I meant these buttons.

You should be able to change the buttons order (is buttons even the right term?) on the taskbar (or task list) with Xfce.

Left click and hold down, then drag the buttons.

When I click, hold and drag it, the button (I think it's the right term...) moves with the cursor like a picture when you drag it from browser. But whenever and wherever I release it, the picture goes back to it's button and there's no way I can change their order like this...

It works on Xfce 4.6.1 on Slackware64 13.1 as cascade9 described.

Kde 4.3.5, I have an option in "settings" menu of the "task manager" by which I can "sort" and "group" those "minimized windows", see if you have something similar.

AFAIK there is nothing under the Xfce settings for the Task List but if you right click in an empty area of the Task List and click on Properties ... on my system the only box ticked is "Fixed length (pixels)"; the setting is 640.

This feature was available in Xfce 4.6 but was removed in 4.8.

There is a bug report, to which the developers replied and said that they removed the feature because it makes things less complicated for them and they thought that users don't care much for it.

Maybe the best thing to do now is to add our voices to other peoples' voices and comment on the bug report so that the developers would realize that user do actually care for this, and maybe make this feature available again in later versions of Xfce.

it's possible
 

just go to: Windows Button preferences and select the sorting order: "None, allow drag-and-drop"
And that's it.