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.

Fixed: added a simple extension-based filtering to Folder/PK3/PK7 resources to prevent loading data from unrelated resources.
Fixed: there can be several entries of the most ZDoom text lumps in WADs. Previously only the first one was processed.
Internal: rewritten DirectoryFilesList to use one collection instead of two.

Added, Sectors, Linedefs, Things modes: map element selection order of rectangular selection is now direction-dependent.

Fixed, Visual mode, UDMF: in some cases Fade color was not applied to floor and ceiling surfaces of 3d floors.
Fixed, Visual mode: in some cases not all sidedef geometry was updated when updating sectors with Plane Align (181) action. Also fixed some more unnecessary geometry updates.
Fixed, Linedefs mode, Things mode: in some cases deleting linedefs/things caused a crash when trying to update text labels.
Fixed, Draw Lines mode: in some cases the drawing was prematurely finished when "Auto-finish drawing" option was enabled.

Added, Draw Lines mode: additional guidelines and horizontal/vertical line lengths can now be displayed for currently drawn line using "Show guidelines" top menu button.
Changed, Draw Lines mode: line angles are now shown only when "Show guidelines" mode is enabled.
Fixed, Draw Lines mode: in some cases "Snap to cardinal directions" mode was snapping only to diagonals.
Fixed, Draw Lines mode: snap to geometry behaved incorrectly when "Snap to cardinal directions" mode was enabled.
Changed, Things mode: dynamic light shape is now drawn using highlight color when a dynamic light thing is highlighted.
Added more sanity checks to MODELDEFS parser.

Added, Visual mode: "Increase/Decrease Scale", "Reset Texture Offsets" and "Reset Local Texture Offsets" actions now work when used on 3d floor sides.
Fixed: CVARINFO parser was unable to parse negative int/float values.
Fixed: in some cases TextLabel text size was checked before it was calculated. 
Internal, Visual mode: reduced the number of unnecessary geometry updates when changing map geometry.
Updated ZDoom_DECORATE.cfg (atan2 and VectorAngle).

Fixed, Linedefs mode: fixed a crash on undoing linedef draw when trying to update a text label for disposed linedef.

Fixed, Script Editor: fixed infinite loop when trying to search for empty string.
Changed, Linedefs mode: selection labels are now positioned in a less line angle obscuring way.
Changed, Draw Lines mode: text label background alpha didn't match the alpha of the labels used in other classic modes.
Updated ZDoom_ACS.cfg (SetMusicVolume).
Updated ZDoom ACC (SetMusicVolume).

Added: dynamically added side panel tabs now play notify animation when the side panel is collapsed.
Added, Game configurations, ZDoom: added Sector effect 90 (Skybox sector).

Internal: added CVARINFO parser.

Updated ZDoom_DECORATE.cfg.

Added, Game configurations: added "Enum option + enum bits":26 action argument type. It can be used when an argument combines both exclusive and bit flag values.
Updated, Game configurations: some linedef action arguments now use type 26.
Updated documentation ("Game Configuration - Action Argument Settings").
Updated ZDoom ACC (APROP_MaxStepHeight and APROP_MaxDropOffHeight).

Re-fixed: fixed a crash when determining sprite angles when there was more than one sprite for the same frame and angle.

Fixed: fixed a crash when determining sprite angles when there was more than one sprite for the same frame and angle.

Fixed: fixed a crash when determining sprite angles when there were sprites for both rotated (like TESTA2A8) and non-rotated (like TESTA0) versions of the same frame.
Fixed, Tags Selector control, UDMF: in some cases tags adding/removing worked unreliably when mixed tag values were used.
Fixed, Arguments control: in some cases ending colon was not appended to argument names.
Updated ZDoom_ACS.cfg.
Updated ZDoom_DECORATE.cfg.

Fixed, Visual mode: in some cases "Flood-fill textures" actions were not working when "use long texture names" Map Options setting was enabled.

Added, Game configurations: added "Polyobject number":25 argument type. When set, used polyobject numbers will be displayed in the action argument dropdown.
Added, Map Analysis mode: Polyobj_ExplicitLine action was not checked by "Check polyobjects" check. 
Updated ZDoom_linedefs.cfg and Hexen_linedefs.cfg (polyobject number linedef args now have type 25).
Updated documentation ("Game Configuration - Action Argument Settings").

Added, GLDEFS parser: light name can have spaces too, so it also can be quoted...
Removed some excessive quote stripping from most of the ZDoom-related text parsers.
Some parsing error reporting improvements in MODELDEF and GLDEFS parsers.
Added a special warning when a texture/flat is overridden by a cameratexture.

MODELDEF parser: rewrote most of the parser logic. Now it picks actor model(s) based on Frame / FrameName properties.

Fixed, Things mode: in some cases selection labels were not updated after editing a thing.
Fixed, Things mode: selection labels were positioned incorrectly on things with FixedSize setting.
Fixed, Sectors mode: fixed a crash when selecting self-referencing sector when selection labels were enabled.
Fixed, Visual mode: in some cases Auto-align texture actions were not working when "use long texture names" Map Options setting was enabled.
Fixed, MD2/MD3 loader: available animation frames upper bound check was performed incorrectly, which would cause a crash in some very special cases.
Fixed, Game configurations: most Hexen/ZDoom teleport actions use TeleportDests as teleport targets, not MapSpots.

Added, Linedefs mode, Things mode: selection numbers can now be displayed and can be toggled using the "View Selection Numbering" mode toolbar button.
Added, Linedefs mode, Things mode: sector tags can now be displayed and can be toggled using the "View Sector Tags" mode toolbar button.
Fixed, Classic modes, DB2 bug: in some cases text label size was queried before it was calculated, resulting in text labels being rendered when they shouldn't.
Updated ZDoom_DECORATE.cfg (A_LogFloat).

Added, Game configurations: added "targetclasses" argument property. Can be used with argument type 14 (Thing Tag). When set, only things of given classes will be shown in the argument dropdown list in Edit Things window.
Changed, Classic modes: when "Fixed Things Scale" option is enabled, things will now switch to fixed size rendering mode when their visible size is less than 48 pixels.
Changed, Classic modes: changed the fixed size of things with FixedSize setting to 28 pixels.
Updated documentation ("targetclasses" argument property).

Fixed, Classic modes: thing sprite should always be rendered when it's size is affected by "Fixed Things Scale" option or FixedSize setting.
MAPINFO parser: removed a misleading warning.

Rearranged some settings in the Preferences window.

Changed, Texture Browser window: "All" textures group is now saved/reselected like the rest of the texture groups when closing/opening the window.
Changed, Classic modes: bigger Thing arrows are now rendered when thing sprite rendering is skipped.
Changed, Classic modes: when "Fixed Things Scale" option is enabled, thing size stays at 2x scale instead of 1x when extra bounding box is rendered.
Added Preferences -> Appearance -> "Things transparency (Things mode)" slider.
Renamed Preferences -> Appearance -> "Things transparency" to "Things transparency (other modes)".
Externalized thing bounding box and arrow texture, used to render things in Classic modes (Textures/ThingTexture2D.png).
Updated ZDoom_DECORATE.cfg (A_SetUserVarFloat, A_SetUserArrayFloat).

Internal, API: TextLabels can now display multi-line text, their font can be changed, they can have a background.

Added Preferences -> Appearance -> "Things transparency" slider. It controls Things transparency in all classic modes except Things mode.
Added Preferences -> Appearance -> "Hidden Things transparency" slider. It controls transparency of Things hidden by Things filter in Things mode, of all things :)

Fixed, Script Editor: in some cases unwanted characters were inserted when using keyboard shortcuts.
Fixed, Script Editor: auto-completion was not invokable when typing ACS directives.

Fixed occasional TreeView flickering in Edit Things window, Browse Action window and Tag Explorer panel.
Updated Thing category icons in the Edit Things window. They now have "opened" and "closed" states.
Internal: added BufferedTreeView to the core controls.
Updated ZDoom game configurations (sector crush mode).
Updated ZDoom ACC.

Added, Preferences -> Appearance: added "Anisotropic filtering" and "Edge Antialiasing" settings. Also regrouped some settings.
Added, "Check polyobjects" error check: added a check for matching Polyobject and Mirror Polyobject numbers of Polyobj_StartLine action.
Changed, Visual mode: anisotropic filtering is now always applied (previously it was applied only when bilinear filtering was enabled).
Fixed, Visual mode: in some cases light values were incorrectly transferred between 3d floors and regular floors/ceilings.
Fixed, ACS parser: includes for each library must be stored separately (fixes inability to compile a script with an included library, which in turn includes files already included by the script).

Fixed, Map Analysis mode, DB2 bug: "Flip Linedef" fix for "Check line references" check was applied incorrectly.

Fixed, "Check Polyobjects" error check: an error is no longer added when "Mirror Polyobject Number" of "Polyobj_Startline" is 0.
Fixed, "Find and Replace" mode: "Find and Replace" window no longer closes when no results are found and Replace mode is enabled.
Changed, "Find and Replace" mode: renamed some search modes for better grouping.

Fixed, Visual mode: alpha-based texture picking didn't work correctly on HiRes images.
Fixed, Visual mode: fog density was calculated incorrectly for things lit by dynamic lights.
Fixed, Edit Sector window, UDMF: "Fade" and "Light" color pickers initial values were incorrect when displaying mixed values.
Fixed, Edit Thing window, UDMF: "Color" color picker initial value was incorrect when displaying mixed values.