Hi hilbert hussen,
I hope I understood what you asked for...
* You can select the hidden Panel in propery windows Combobox (on top of the property there is a list of all elements on your form, you will not see it but you can edit its properties
* You can temporarilly bring the hidden Panel to front (in VS there is a "Format" menu which appears whenever you focus the Forms designer) - but do not forget to rearrange it later.
* If you are hidding some control in this way chances are high you have some code to set the z-Order (or hide the overlaying Panel) - you could work without designer and just do your changes in code.
Other from that "
workarrounds" I don't know a good way to bring hidden controls to front during design (though I didn't need that very often in the past when I worked with WinForms)
Kind regards Johannes