Like I mentioned above, you can right click the named tab, or the file name in the Files window to choose Open in Browser (which is the old Preview in Browser). You can also make a modification to one of DW's program files to kill Real Time Preview entirely and go back to Preview in Browser (now called Open in Browser)...
1. Close DW and go to...
Windows: C: > Program Files > Adobe > Adobe Dreamweaver CC 2017 > configuration > Menus > MM
Mac: Applications > Adobe Dreamweaver CC 2017 > configuration > Menus > MM
(I think, I don't have a Mac to test)
2. Open the file "PIB_Dynamic.js"
2a. As always, make a backup in case something goes sideways. Add _old at the end of the back-up's file name.
3. Search for the text "dw.browseDocument". There are 3 spots with that code, but the first two are just comments. The right one should be on or about line 433, and change the text "isPIB" to "true"
The finished line of code will look like...
dw.browseDocument(dw.getDocumentPath('document'),theBrowser, "-1"/*help argument*/, false /*use temp doc*/, true);
4. Save the file to your desktop
5. Drag the file into the original location from Step 1. You will be prompted for your Admin credentials in order to make the copy/replacement
In DW CC2019, they finally gave us a toggle under Edit > Preferences > Real-time Preview to check Default to Static Browser Preview (use preview in browser) instead of RTP.