For when editing svg's in tiddler edit mode, to manually select section view and zoom in & out of svg in the preview window-- temporarily edit the svg viewBox and width attributes.
<svg viewBox="0 0 100 100" width="100">
To change view to certian area:
left half only of svg:
viewBox="50 50 50 50"
To zoom in: width="200"
or edit 3rd & 4th number of viewBox smaller:
viewBox="0 0 50 50"
To zoom out: width="50"
or edit 3rd & 4th number of viewBox smaller:
viewBox="0 0 200 200"
Combine the two to view sections with zoom in.
The viewBox and width attributes can be changed back to original settings when done editing.