The size of the wire shadows in the compositor becomes buggy as the compositor window v-size changes. Attached is a picture demonstrating the bug. The top window has been scaled slightly larger than the bottom one, and as a result the shadows are clearly messed up. This happens even for a completely new blend file, but only happens on my windows 7 machine, not my XP. System information is as follows:

============================================
= Blender 2.60 (sub 1) System Information =
============================================


Blender:
============================================

version 2.60 (sub 1), revision 41618. Release
build date: 2011-11-07, 10:34:52
platform: Windows:64bit
binary path: C:\Program Files\Blender Foundation\Blender\blender.exe
build cflags: /nologo /Ob1 /J /W0 /Gd /we4013 /wd4018 /wd4244 /wd4305 /wd4800 /wd4065 /wd4267 /openmp -O2 -DNDEBUG -DWIN32 -D_CONSOLE -D_LIB -D_CRT_SECURE_NO_DEPRECATE -DWIN64 -DWITH_MOD_FLUID -D__LITTLE_ENDIAN__ -DWITH_AUDASPACE
build cxxflags: /nologo /Ob1 /J /W0 /Gd /we4013 /wd4018 /wd4244 /wd4305 /wd4800 /wd4065 /wd4267 /openmp /EHsc -O2 -DNDEBUG -DWIN32 -D_CONSOLE -D_LIB -D_CRT_SECURE_NO_DEPRECATE -DWIN64 -DWITH_MOD_FLUID -D__LITTLE_ENDIAN__ -DWITH_AUDASPACE
build linkflags: /SUBSYSTEM:CONSOLE /MACHINE:X64 /STACK:2097152 /OPT:NOREF /INCREMENTAL:NO /NODEFAULTLIB:msvcrt.lib /NODEFAULTLIB:msvcmrt.lib /NODEFAULTLIB:msvcurt.lib /NODEFAULTLIB:msvcrtd.lib
build system: SCons

Python:
============================================

version: 3.2 (r32:88445, Mar 2 2011, 16:59:21) [MSC v.1500 64 bit (AMD64)]
paths:
C:\Program Files\Blender Foundation\Blender\2.60\scripts\addons
C:\Program Files\Blender Foundation\Blender\2.60\scripts\startup
C:\Program Files\Blender Foundation\Blender\2.60\scripts\modules
C:\Program Files\Blender Foundation\Blender\2.60\python
C:\Program Files\Blender Foundation\Blender\python32.zip
C:\Program Files\Blender Foundation\Blender\2.60\python\DLLs
C:\Program Files\Blender Foundation\Blender\2.60\python\lib
C:\Program Files\Blender Foundation\Blender
C:\Program Files\Blender Foundation\Blender\2.60\scripts\addons\modules

Directories:
============================================

scripts: ['C:\\Program Files\\Blender Foundation\\Blender\\2.60\\scripts']
user scripts: None
datafiles: C:\Users\mardgase\AppData\Roaming\Blender Foundation\Blender\2.60\datafiles\
config: C:\Users\mardgase\AppData\Roaming\Blender Foundation\Blender\2.60\config\
scripts : C:\Users\mardgase\AppData\Roaming\Blender Foundation\Blender\2.60\scripts\
autosave: C:\Users\mardgase\AppData\Roaming\Blender Foundation\Blender\2.60\autosave\
tempdir: C:\Users\mardgase\AppData\Local\Temp\

OpenGL
============================================

renderer: ATI Radeon HD 4200
vendor: ATI Technologies Inc.
version: 3.3.10750 Compatibility Profile Context
extensions:
GL_AMDX_debug_output GL_AMD_conservative_depth GL_AMD_debug_output
GL_AMD_depth_clamp_separate GL_AMD_draw_buffers_blend
GL_AMD_name_gen_delete GL_AMD_performance_monitor
GL_AMD_sample_positions GL_AMD_shader_stencil_export
GL_ARB_ES2_compatibility GL_ARB_blend_func_extended
GL_ARB_color_buffer_float GL_ARB_copy_buffer GL_ARB_depth_buffer_float
GL_ARB_depth_clamp GL_ARB_depth_texture GL_ARB_draw_buffers
GL_ARB_draw_buffers_blend GL_ARB_draw_elements_base_vertex
GL_ARB_draw_instanced GL_ARB_explicit_attrib_location
GL_ARB_fragment_coord_conventions GL_ARB_fragment_program
GL_ARB_fragment_program_shadow GL_ARB_fragment_shader
GL_ARB_framebuffer_object GL_ARB_framebuffer_sRGB
GL_ARB_geometry_shader4 GL_ARB_get_program_binary
GL_ARB_half_float_pixel GL_ARB_half_float_vertex GL_ARB_imaging
GL_ARB_instanced_arrays GL_ARB_map_buffer_range GL_ARB_multisample
GL_ARB_multitexture GL_ARB_occlusion_query GL_ARB_occlusion_query2
GL_ARB_pixel_buffer_object GL_ARB_point_parameters GL_ARB_point_sprite
GL_ARB_provoking_vertex GL_ARB_sampler_objects
GL_ARB_seamless_cube_map GL_ARB_separate_shader_objects
GL_ARB_shader_bit_encoding GL_ARB_shader_objects
GL_ARB_shader_precision GL_ARB_shader_stencil_export
GL_ARB_shader_texture_lod GL_ARB_shading_language_100 GL_ARB_shadow
GL_ARB_shadow_ambient GL_ARB_sync GL_ARB_texture_border_clamp
GL_ARB_texture_buffer_object GL_ARB_texture_buffer_object_rgb32
GL_ARB_texture_compression GL_ARB_texture_compression_rgtc
GL_ARB_texture_cube_map GL_ARB_texture_env_add
GL_ARB_texture_env_combine GL_ARB_texture_env_crossbar
GL_ARB_texture_env_dot3 GL_ARB_texture_float
GL_ARB_texture_mirrored_repeat GL_ARB_texture_multisample
GL_ARB_texture_non_power_of_two GL_ARB_texture_rectangle
GL_ARB_texture_rg GL_ARB_texture_rgb10_a2ui GL_ARB_texture_snorm
GL_ARB_timer_query GL_ARB_transform_feedback2
GL_ARB_transform_feedback3 GL_ARB_transpose_matrix
GL_ARB_uniform_buffer_object GL_ARB_vertex_array_bgra
GL_ARB_vertex_array_object GL_ARB_vertex_buffer_object
GL_ARB_vertex_program GL_ARB_vertex_shader
GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array
GL_ARB_window_pos GL_ATI_draw_buffers GL_ATI_envmap_bumpmap
GL_ATI_fragment_shader GL_ATI_meminfo GL_ATI_separate_stencil
GL_ATI_texture_compression_3dc GL_ATI_texture_env_combine3
GL_ATI_texture_float GL_ATI_texture_mirror_once GL_EXT_abgr
GL_EXT_bgra GL_EXT_bindable_uniform GL_EXT_blend_color
GL_EXT_blend_equation_separate GL_EXT_blend_func_separate
GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_compiled_vertex_array
GL_EXT_copy_buffer GL_EXT_copy_texture GL_EXT_direct_state_access
GL_EXT_draw_buffers2 GL_EXT_draw_instanced GL_EXT_draw_range_elements
GL_EXT_fog_coord GL_EXT_framebuffer_blit
GL_EXT_framebuffer_multisample GL_EXT_framebuffer_object
GL_EXT_framebuffer_sRGB GL_EXT_geometry_shader4
GL_EXT_gpu_program_parameters GL_EXT_gpu_shader4 GL_EXT_histogram
GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil
GL_EXT_packed_float GL_EXT_packed_pixels GL_EXT_pixel_buffer_object
GL_EXT_point_parameters GL_EXT_provoking_vertex GL_EXT_rescale_normal
GL_EXT_secondary_color GL_EXT_separate_specular_color
GL_EXT_shadow_funcs GL_EXT_stencil_wrap GL_EXT_subtexture
GL_EXT_texgen_reflection GL_EXT_texture3D GL_EXT_texture_array
GL_EXT_texture_buffer_object GL_EXT_texture_compression_latc
GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc
GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp
GL_EXT_texture_env_add GL_EXT_texture_env_combine
GL_EXT_texture_env_dot3 GL_EXT_texture_filter_anisotropic
GL_EXT_texture_integer GL_EXT_texture_lod GL_EXT_texture_lod_bias
GL_EXT_texture_mirror_clamp GL_EXT_texture_object
GL_EXT_texture_rectangle GL_EXT_texture_sRGB
GL_EXT_texture_shared_exponent GL_EXT_texture_snorm
GL_EXT_texture_swizzle GL_EXT_timer_query GL_EXT_transform_feedback
GL_EXT_vertex_array GL_EXT_vertex_array_bgra
GL_IBM_texture_mirrored_repeat GL_KTX_buffer_region GL_NV_blend_square
GL_NV_conditional_render GL_NV_copy_depth_to_color
GL_NV_explicit_multisample GL_NV_float_buffer GL_NV_half_float
GL_NV_primitive_restart GL_NV_texgen_reflection GL_NV_texture_barrier
GL_SGIS_generate_mipmap GL_SGIS_texture_edge_clamp GL_SGIS_texture_lod
GL_SUN_multi_draw_arrays GL_WIN_swap_hint WGL_EXT_swap_control