I think would be helpful to view all source code in a single screen only zooming out.
The code should be represented as vertical panels putted side by side.
Look at the screenshot (modified with gimp).
Geany - zoom out view
I wonder if it make sense to me to zoom out 5 till 10 times, until the font becomes unreadable. It means you'll have to recognize (your's or other's) code depending on the indent and line length solely. On the other hand, if Geany can display more information on the screen, you'll most likely benefit from it, as less scrolling is required while editing several functions in parallel.
Imagine you could zoom in/out less drastically, but something like -40% till +100%. This is effectively already available if you just choose a smaller (6pt) or larger font (20pt), see the preferences tab. Firefox has a similar zoom-in/out approach in which you allowed to dynamically zoom-in, zoom-out or zoom-reset using the Control key combined with respectively '+' , '-' and '0'.
As you showed in the picture, the scaling is the one part, the addition of multiple text columns of the same file is another part. This would require multiple scintilla widgets (correct me if I'm wrong on this), which will take some programming effort. As an extra argument to propose this newspaper-style layout: imagine how many people nowadays have a wide screen monitor. In my case, using the default 10pt font, and the long line marker ar position 72, the monitor could easily display three columns, including line numbers, marker margin and folding indicator.
Note: we already have the Split Window plugin that can do one extra view side by side.
The disadvantage of my enthousiasm is that I didn't look carefully. The control keys for zooming-in and and out are already there. That's great!
The only remaining difference in behaviour is the "zoom normal size" or "zoom reset" as it is called in FireFox, which is controlled with a Ctrl + '0' key combination. I certainly would appreciate the Ctrl+'0' control, unless you can convince the Mozilla team to switch to Alt-N :-)
I tested the zooming function in combination with the split window plug-in. Unfortunately, the splitted window doesn't respond to the zooming commands, neither in horizontal nor vertical split mode. Shall I submit a bug to the geany plug-in project?
The same for the feature to have a continuous 'newpaper view': scrolling the left window will automatically scroll the right window, which continuous displaying the adjacent text of the left column.
Maybe the original author of this feature request (anonymous) has some other ideas?
We could add a 'Zoom reset' keybinding.
The Split Window plugin is far from ideal. Most editing features don't work, it's really only useful for a 2nd view. If I have time I might work on it.
The Split Window plugin is not intended to scroll in step with the main editor.
I added the Ctrl+0 key in revision 4786. This is partly useful as the dynamic key procedure keybindings_set_item() allows only one key combination to be connected. However, There are two '0's, one above the 'O' and 'P' keys, the other on the numeric keypad. In gdk/gdkkeysyms.h these are defined seperately as respectively GDK_0 and GDK_KP_0. ORing them is not allowed (GDK_0 | GDK_KP_0), and connecting twice only keeps the last one active.
I think this is OK - the user can configure whichever binding they want to use now.