I've found using canvases and panels to be quirky - often, mounting a canvas to a panel doesn't yeild the same results as attaching other gadgets to a panel.
In my Map Editor, I use tabs - the panels are attached to the tabber, with buttons and so forth attached, while the canvases are attached to the tabber directly (NOT the panel). When a tabber is selected, I hide the relevant panel and canvas, then show the new panel and canvas.
In my Map Editor, I use tabs - the panels are attached to the tabber, with buttons and so forth attached, while the canvases are attached to the tabber directly (NOT the panel). When a tabber is selected, I hide the relevant panel and canvas, then show the new panel and canvas.