Xshell offers a transparency setting.

To Set Window to Appear Transparent:

Select [Transparent] from the [View] menu.
Open the Options dialog box.
Set transparency in the [View] tab.
Set [Opacity]. The smaller the opacity is, the more transparent the Xshell window becomes.
If [Make window opaque on mouse over] option is selected, Xshell window is displayed opaque while mouse is over the window even when it is set to display Xshell window transparent.
If [Always on Top when it is transparent] option is selected, Xshell window is displayed at the top of all windows.

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