Hello Min,

Please take a look on the answers of your questions:

MIN you jin said:

I want to make space gap between the docking panel and the Ribbon tool. How can I do?

It is possible to increase the space between Ribbon and DockAreaPane using the PaddingTop property. This option is available when your Pane is Pinned = True.  When the pane is unpinned one possible approach to increase the space is through CreationFilter

 

MIN you jin said:

  I want to make the space gap between Ribbon tab and Form title bar like screen below. How can I do? And, Can I assign randomly the height of Ribbon tab?

One possible approach could be if you modify the Style property of your UltraToolbarsManager . If you want to keep your current style, then you should use CreationFilter. At that moment there is not such property

MIN you jin said:

  When I did Docking two panels of A and B, a gray line comes out between A and B

Looking on the screenshots is difficult to guess what is this line. It could be the borders of your controls (in panel A and B). If so, you could set Border property of your controls to NONE. The line could be a splitter. If so, you could play with appearance properties of the splitter . Please give us more details about your scenario or send us small sample .

 

MIN you jin said:

 When I assign Ribbon tool on Form and fill entire screen by using Docking panel. Can I make space gap between Ribbon toll and Docking panel? - Possible without putting arbitrarily Control?

There are few possible options depending of your scenario.

Option 1: If you have a DockAreaPane then you could set  PaddingTop property

Option 2: If you have not a DockAreaPane, then you could use Anchor property of your control instead of Dock = Fill property.

Option 3: You could include a Panel with Dock = Top.  The height  of that panel will determinate the space between your Ribbon and content below

Let me know if you have any questions.