arrow lengths are scaled consistently regardless of direction and aspect ratio (ax.set_aspect()). This fixes issue #2575.

Author: jewettaijfc

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-## [2.9.0rc1] - 2025-06-10
+## [2.9.0rc1] - 2025-06-16
 
 ### Added
 
@@ -36,6 +36,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Validation for `CustomGridBoundaries`, which was previously allowing unsorted arrays and arrays with less than two entries.
 - `DiffractionMonitor` results to apply finite grid field corrections for higher precision when comparing e.g. to `FluxMonitor` computations of total power.
 - Bug when validating the grid resolution near `CoaxialLumpedPort`.
+- Arrow lengths are now scaled consistently in the X and Y directions,
+  and their lengths no longer exceed the height of the plot window.
 
 ### Changed
 - Relaxed bounds checking of path integrals during `WavePort` validation.

tidy3d/components/geometry/base.py

@@ -2292,7 +2292,9 @@ def _cb(event):
             event.canvas.mpl_disconnect(arrow.set_shape_cb[0])
 
             transform = arrow.axes.transData.transform
-            scale = transform((1, 0))[0] - transform((0, 0))[0]
+            scale_x = transform((1, 0))[0] - transform((0, 0))[0]
+            scale_y = transform((0, 1))[1] - transform((0, 0))[1]
+            scale = max(scale_x, scale_y)  # <-- Hack: This is a somewhat arbitrary choice.
             arrow_length = ARROW_LENGTH * event.canvas.figure.get_dpi() / scale
 
             if bend_radius: