Fixed, Drag Linedefs, Drag Vertices, Edit Selection modes: in some cases sidedefs were incorrectly removed when modifying a closed section of a multi-part sector.
Fixed, Drag Linedefs, Drag Vertices, Drag Sectors, Edit Selection modes: in some cases sidedef textures were not adjusted after applying the modes, leaving middle textures on double-sided lines.

Added, Edit Selection mode: Added "Adjust height" setting. It can be used to adjust floor/ceiling height of selected sectors based on the sector selection was in and the sector selection was moved into.
Removed "Adjust heights to match relatively with surrounding sector" option from Preferences -> Pasting, because sector height adjustments are now handled by Edit Selection mode.
Fixed, Sector info panel: in some cases 0 deg. floor/ceiling texture rotation was triggering texture offset/scale/rotation UI parts to be shown.
Fixed even more cases when sidedefs belonging to linedefs, which were moved on top of existing linedefs, were incorrectly reassigned when applying Edit Selection and Drag Geometry modes.
Fixed, Bridge mode: in some cases calculated floor/ceiling heights were not applied to the sectors created by the mode.
Changed, internal: changed program's CurrentCulture to InvariantCulture.

Changed, internal: made TextLabel and IRenderer2D public properties compatible with DB2 implementation.
Fixed some more cases when sidedefs belonging to linedefs, which were moved on top of existing linedefs, were incorrectly reassigned when applying Edit Selection and Drag Geometry modes.
Fixed, Map Analysis mode: error checks must be updated after switching map format.

Added "safeboundary" game configuration property. The value determines the maximum map bounding box size considered to be safe by "Check map size" error check.
Changed, Map Analysis mode: some checks are now available only under certain conditions (for example, "Check polyobjects" is now available only when the map is in Hexen or UDMF map format).
Updated documentation ("Game Configuration - Basic Settings" page).

Added: sectors are now split into multiple sectors when their shape is divided into several closed shapes by drawing new geometry or dragging existing geometry using Edit Selection and Drag Geometry modes.
Fixed: in some cases sidedefs belonging to linedefs, which were moved on top of existing linedefs, were incorrectly reassigned when applying Edit Selection and Drag Geometry modes.
Fixed: Tag Explorer update fix from R2630 was accidentally placed in an UDMF-only if-block.
Updated ZDoom_DECORATE.cfg (A_WeaponOffset).
Updated documentation ("(G)ZDoom text lumps support" page).

Fixed, Tag Explorer: in some cases (for example, when geometry was removed implicitly by dragging geometry) the list was not updated.
Fixed: in some cases generalized sector effect detection logic failed to detect a valid generalized effect.
Fixed, Action selector control: action label was not updated when changing action number from one generalized effect to another.

Fixed a crash when trying to store a custom field with "Byte Angle" type.
Fixed: in some cases custom field types stored in the map's .dbs file were not applied when loading a map. 

Fixed, Visual mode: texture offsets were updated multiple times when moving texture offsets of several extrafloor sides linked to the same control sidedef.
Fixed, Visual mode: sidedef geometry of sectors affected by "Copy Slope" effect was not updated when the source slope was modified.

Added, DECORATE support: #region blocks are now used as thing categories ("//$Category" actor block definition overrides these). Additional category-wide special comments are now available (see documentation).
Updated documentation ("DECORATE keys" page).

Added, Sound Environments mode: sound environments of the same type are now colored using the same color.
Added, Sound Environments mode: current sound environment is now highlighted (can be toggled using "Toggle Highlight" action).
Added: Tag selectors now have up/down buttons.
Fixed, Sound Environments mode: sound environments were not updated after performing Undo/Redo actions.
Fixed, Sound Propagation mode: sound zones were not updated after performing Undo/Redo actions.
Internal: moved "Toggle Highlight" action to the core, also changed it's category to "View".
Internal: "Toggle Highlight" action state is now saved in the Program configuration.
Updated ZDoom_DECORATE.cfg (GetZAt).
Updated ZDoom_linedefs.cfg (Sector_SetPortal args).

Changed, Visual mode: "Auto-align textures" and "Paste Textures Floodfill" actions now use visual mode geometry to determine whether a sidedef part should be processed. This fixes inability to apply said actions to sidedef parts only visible because of slopes.
Fixed, Visual mode: both "With same texture" and "With same height" Select modifiers are now checked when both of them are used at once (previously a sidedef part/floor/ceiling was selected when any of those matched).

Fixed, all drawing modes: in some cases incorrect sector shape was constructed when updating sector shapes after drawing new lines, which resulted in nearby sectors being merged into sector(s) affected by linedefs drawing.

Added: when "sidedefcompressionignoresaction" property is set to false, sidedefs, which belong to a line with a non-zero action or tag, will be skipped when compressing sidedefs.

Fixed, Find and Replace mode: fixed an exception when trying to assemble search result label for a named script without arguments.

Added, Find and Replace mode: action arguments are now displayed in "Linedef Action and Arguments" and "Thing Action and Arguments" search results.

Fixed, Linedefs mode: fixed inability to highlight linedefs when "Stitch geometry within" setting was set to 0.
Fixed, Visual mode: fixed a crash when performing "Auto-align textures" actions on selected sidedefs when there were also floors/ceilings selected.

Game configurations: added "sidedefcompressionignoresaction" property. When set to true, sidedefs will be compressed regardless of linedef action (DB2 behaviour). When set to false, sidedefs, which belong to a line with an action, will be skipped when compressing sidedefs. Default value is false.

Fixed, MODELDEF parser: negative frame number of FrameIndex definition should be treated as "skip model rendering". Also added some more corner case handling.
Fixed, Sound Environment mode: in some cases the view was not updated after updating sound environments.
Added, Sound Environment mode: Sound environment things of currently highlighted sound environment are now highlighted.

Fixed: in some cases sidedefs were incorrectly reassigned when applying Edit Selection and Drag Geometry modes.

Fixed, DECORATE parser: editor comments caused the parser to skip next actor definition when used in incorrect scope.

Fixed, Visual mode: rendering effects of "Slope floor/ceiling to here" things (9500/9501) should not be applied when their arg0 is 0.

Fixed, Visual mode: "Rotate CW"/"Rotate CCW" actions should update thing-based effects when used on Things.
Added/restored, Visual mode: restored "Move Texture Left/Right/Up/Down by 8" actions, added "Move Texture Left/Right/Up/Down by Grid Size" actions (default keys are Ctrl+arrow keys).
Fixed, Game configurations: Hexen's Bell actor was missing "hangs" flag.

Fixed, Script Editor: rewritten keyboard shortcut handling logic. Now it's (hopefully) no longer possible to insert unrelated characters when using keyboard shortcuts. Also "Duplicate line" (Ctrl-D) command was disabled for no reason.

Fixed, Sectors mode: tags and effect labels were displayed instead of selection number labels after disabling, then enabling selection numbers when there were sectors with tags or effects selected.

Fixed, Things mode: fixed a crash when switching to Things mode when more than 256 things were selected.

Added: holding Control key while switching to/from Visual mode will now temporarily disable position synchronization (works only when 'Synchronize camera position between 2D and 3D modes' Preferences option is enabled).
Fixed severe lock-up after finishing dragging many vertices/linedefs/sectors in Classic modes.
Updated documentation ("Synchronizing camera position").

Updated ZDoom_DECORATE.cfg (ALLOWTHRUFLAGS flag).

Fixed, Classic modes: fixed excessive redraws and text label / sector highlight flickering when using rectangular selection with modifier keys.

Fixed, Visual mode: in some cases translucency was ignored on inner top sides of translucent 3d floors.
Internal, Script Editor: moved some setup/auto-completion logic to separate classes.
Updated ZDoom_DECORATE.cfg (A_QuakeEx).

Fixed, Visual mode: 3d floor outer sides were not updated after toggling rendering effects off, then on.
Updated ZDoom_DECORATE.cfg (GetAngle function). 

Fixed, Game configurations window: new test engine entry was still added when pressing "New Test Engine" button, then canceling the browse dialog.
Fixed, general interface: in some cases opening "Test Map" drop-down resulted in an exception when trying to access a disposed/non-existing test engine icon.

Added, Drag Vertices\Linedefs\Sectors\Edit Selection modes: sidedefs facing outside of current selection are now reattached/added/removed after moving the selection.
Currently this will work as intended only if the selection ends up either completely inside a single sector or completely outside of any sector. Also this logic won't be applied if the selection contains the lines with only start or end vertex selected.
Internal: some TextLabel refactoring.