I would suggest that when opening preexisting glyphs in new windows that it follows the style that is selected in the font view.
For example, currently if you open a glyph such as “a” in a new tab viewing your italic style, then go back to the font view and try to reopen the glyph in the regular style, it simply opens the existing tab instead of making a new one or changing the tab to be regular. This is disruptive and happens more often than you would think.
I would hope that this gets addressed more like a bug. But I am open to suggestions.
If you’re already starting out in the edit tab where you have the glyph open, the latter (switch to the regular master) is most easily done by just switching directly in the tab; and I would think it’s easier to achieve the former (open the other master in a new tab) by hitting Cmd + T to open the same glyph in a new tab and then switch to the master you want there.
But it’s different, of course, if you don’t start out in the edit tab. If you’re looking at the regular master in the font view, with lots of open edit tabs, and you then click to open a without realising a is already open in the italic master, simply switching to that tab is not expected behaviour. As far as the user is concerned, what happened was that Glyphs just opened the wrong glyph for you.
I would say opening a glyph that’s already open in a different master should open a new edit tab, rather than switching masters in the already open one.
First: The edit view is kind of like a text view. So you can add many glyphs (don’t overdo it, one paragraph or two)
I would recommend to not switch to the font view but stay in the edit view and add glyphs you like to edit/see. There are various ways to add glyphs.
switch to the text tool (hit the T key). Type what you need. Hit Esc to get back to the edit tool
Cmd+F and type the glyph name (you can use the arrow keys to select glyphs down the list). Hit enter to add the glyph
Cmd+Option+F to open the sample text dialog. arrow keys up and down and Enter to add the line to the edit view. (You can customize the sample strings in Preferences).
You can change the current master like this:
In the toolbar, click the master icon.
Hit Cmd+Option+1-x to select master. This is the most common way to switch masters.
In the layer panel, switch the active layer. This is helpful see different masters next to each there.