I'm really digging Reaper V5 and the Default V5 Theme and have been playing around with the Theme Development/Tweaker and rtconfig to make Reaper more to my liking. YMMV...
I'm no expert Themer but I thought I'd share what I've done so far and hope others would do the same!
FYI: I'm only working with the Large layouts (and deleted most other layouts) so some of this may not work well with other Default V5 theme layouts.
In the Theme Development/Tweaker I played around to see what all of the color/font settings do...
I figured out the main colors used in the Default V5 theme and tweaked the colors to remove all of the lines (shadow / highlight, etc...) in the background, to make the background more flat and interconnected.
https://i.imgur.com/GqEdE2I.png
https://i.imgur.com/KNLQpgz.png
I tweaked the Theme Development/Tweaker and the I/O and Window List colors using the main colors from the Default V5 theme. These settings affect many of the windows in Reaper.
https://i.imgur.com/p2oy4xW.png
*I also deleted the tab images from the image folder so that I could use the main background colors for the docker tabs (see image above).
Increased the volume/pan label font in the Theme Development/Tweaker from 8 to 10 (might not work well with other layouts). This increases the size of all the volume labels, pan labels, rec input labels, TCP value readouts and the track numbers in the TCP. The TCP track numbers are now the same size as the MCP (*only can fit 2 digits in TCP).
https://i.imgur.com/DbAg2oR.png
https://i.imgur.com/oKCH5hB.png
In the rtconfig...
I enabled show borders for MCP & TCP. This makes the line between the tracks more prominent.
tcp_showborders 1
mcp_showborders 1
I added this line (thank you cubic13, for the heads up!) to the rtconfig (after the showborders, near the top of rtconfig) to control the TCP Master track minimum height!
tcp_master_minheight 35
Adjusted the TCP height (the last number) so that when I press record I can see that whole TCP track panel (when using my large layout).
tcp_heights 4 24 34 74 ; supercollapsed, collapsed, small(norecarm), recarm size
I designed a large TCP Master layout with only a Label and meter.
For my large TCP layout, I have rec arm, track label, routing, mute, solo & FX on the top line. On the second line is a volume fader and pan knob (just used for reference). All other elements are available on the MCP. I created a standard layout and a layout with the value readouts activated.
For my large MCP layout, in the rtconfig, I set it so that I can always see the track input, pan & volume labels.
set hide_input [0] ; height below which input dropdown is hidden.
set hide_pan_labels [0] ; height below which pan labels are hidden.
set hide_volume_label [0] ; meter area height below which volume label is hidden.
I set the global MCP minimum height so it could be as short as possible before breaking.
mcp_min_height 258
I set my large MCP Master layout the same except I wanted to hide the input space so the Master could be as tall as possible.
set hide_input [900] ; height below which input dropdown is hidden.
set hide_pan_labels [0] ; height below which pan labels are hidden.
set hide_volume_label [0] ; meter area height below which volume label is hidden.
Finally, I copied my theme to create a dark version...
I copied the black fader image from the Session Mixer to use in my large MCP layout.
I copied the dark mute off & solo off images from the Session Mixer to use in my large TCP & MCP layouts.
I used the width knob as the pan knob in my large TCP & MCP layouts (that knob changes to the color of the track background and doesn't stand out as much as the default pan knob).
Tweaked the Theme Development/Tweaker to darken up the arrange area using the colors of the V5 Default theme.
https://i.imgur.com/oKW4XIJ.png
https://i.imgur.com/0aRnUEe.png
That's it for me so far... Anyone have tweaks / ideas to share?