There is a simple fix for this, but you need administrator permissions to modify this original mel command in the Program Files folder.

Open the \Program Files\Autodesk\Maya2019\scripts\others\texturePanelShow.mel file and after the 36. (I think) line add this:

workspaceControl -e -dockToControl $texWin right $texTkCtrl;

So the modified part should look like this:

else if (!`workspaceControl -q -visible $texTkCtrl`)
		workspaceControl -e -visible true $texTkCtrl;
		workspaceControl -e -dockToControl $texWin right $texTkCtrl;

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version 2

If you don’t have administrator permission, you can use the classic solution and use this little script instead of the original command in Maya (replace the command on the shelves where you put the UV Editor icon).

TextureViewWindow;

if (`window -ex polyTexturePlacementPanel1Window`)
workspaceControl -e -dockToControl polyTexturePlacementPanel1Window right UVToolkitDockControl;

Cheers, D