Sector Info panel: in soma cases texture size was shown for unknown/missing textures.

Sector Edit forms: floor/ceiling textures can be cleared with right-click on texture selectors. 

Renamed "Set current textures" to "Set default textures" (I hope that makes more sense now).
Fixed and updated documentation.

Error Checks mode: connected lines with decimal positions were reported as overlapping in some cases.

Fixed "Snap Map Element to Grid" documentation.

"Snap Selected Vertices to Grid" mode: renamed to "Snap Selected Map Elements to Grid". Now it aligns things as well.
Edit forms: some realtime controls were applying relative values incorrectly.

Classic modes: 3D floor indicators can be disabled in preferences (Preferences -> Appearance -> Mark 3D floors in classic modes).
Updated documentation.

Visual mode: fixed a crash when trying to load non existing sprite, defined in configuration or via "//@sprite" parameter in DECORATE.
MissingThing icon is now used when the editor is unable to load thing sprite.
An error is added to error logger when the editor is unable to load thing sprite.

Fixed a crash when executing "Toggle Geometry Effects" (Tab).

Increased maximum zoom level in Classic modes to 3000%.
Added "1 mp" option in grid size menu.
Added "400%" option in zoom menu.
Renamed "Toggle GZDoom rendering effects" action to "Toggle Geometry Effects".
Sync camera position: Visual Camera height is now changed only if camera is above or below current sector.
Classic modes: view was not redrawn after "Test map from current position" action.
"Test map from current position" action: incorrect player start was used when a map had several Player 1 Start things.

Some cosmetic changes in Linedef Edit form.
Link, Unlink and Reset icons can now be properly seen on dark backgrounds.

Tag and script number/name drop downs in Edit forms are now resized to match the width of the longest entry. 
Jitter mode: view was not updated when "Relative" option was toggled.

Some cosmetic changes in uifields management.

Color picked plugin: plugin used incorrect default "lightcolor" value after r1758.

UDMF fields, handled by UI, had broken field types after r1758.
Removed some redundant type casts.

UDMF: added "gravity" thing property to UI.
MAPINFO parser: removed unneeded error notification. 

Made map detection logic a bit more strict. If BEHAVIOUR lump is present, a map can no longer be detected as a map in Doom map format.

"Look Through Selection" action: InterpolationPoint can be handled the same way as SecurityCamera or AimingCamera.

Visual mode: added "Look Through Selection" action (default key is "Y"). This action places visual camera at the same position as selected/highlighted thing and rotates it to match thing's angle. Special handling is available if targeted thing is AimingCamera, MovingCamera or SecurityCamera.
Script editor: pressing "F1" now opens keyword help instead of program manual.
Linedef edit form, Thing edit form: rewritten script support logic. It should now work in the same manner as the rest of controls.
Thing info panel: thing arguments now have proper labels.
Edit forms, UDMF: fields, which are handled by UI, are no longer shown in "Custom" tab.
Visual mode: fixed a crash when loading a model on a video card without Shader model 2.0 support.
Fixed incorrect argument number and changed most of labels in "Cameras and interpolation" section of zdoom_things.cfg.

ACS support: script numbers/names without space between them and script arguments (like 'script 999(void)' or 'script "test"(void)') were not parsed.

Visual mode: fixed major slowdowns and possible out of memory exceptions when viewing a map with lots of missing textures.

Visual mode: rendering was broken on video cards without Shader Model 2.0 support.
Engines list was not updated after changing engine in Test button's drop down.

Visual mode: texture offsets are now clamped to texture size when dragging textures with mouse.
Visual mode, UDMF: when gravity is enabled, sector gravity now affects camera movement.

Sector/Linedef edit form: float values were incorrectly formatted in some cases.

Textures were not loaded properly from PK3/PK7 archives.
Visual mode: restored ability to remove textures using Delete action.
Visual mode: fixed several bugs in Cut/Copy/Paste things actions.
Visual mode: vavoom style 3d floors were not displayed properly.
Visual mode, 3d floors: added support for "RestrictLighting" (2) flag.
Visual mode, 3d floors: inner sides of 3d floors with "swimmable"/"render inside" flags used incorrect brightness value.

Fixed several crashes when trying to load not existing images and models from folder/pk3/pk7 resources.

Visual mode: fixed a crash while changing 3d floor texture offsets when visual sector was not created for 3d floor's control sector.
Visual mode: Info/Warning/Error status messages were not displayed properly when nothing was selected.
Sector Edit form, UDMF: Reset and Link buttons were overlapped in Floor/Ceiling scale controls.

Textures now load up to 2x faster when "mix textures and flats" flag is set in game configuration.
TEXTUREx/TEXTURES: texture will now be created if at least one of it's patches is loaded.
Visual mode: fixed a crash when "Slope floor to here" (9500) or "Slope ceiling to here" (9501) things were not inside sector.
Fixed: flats were not loaded form wads inside Directory and PK3/PK7 resources.
Sector Info Panel, Linedef Info Panel: texture size was shown for unknown textures.

Fixed some errors in non-UDMF <-> UDMF map conversion.
Updated ISS setup script (not tested).
Removed some unused variables.

Texture scale controls now have "Link" button. 
Thing, Sector (UDMF) and Linedef edit forms now work in realtime mode.
Some more fixes in Edit form realtime update stuff.
Removed some unused variables and functions.

Thing Edit form: several thing types can now be selected at once. In this case, a type randomly chosen from selected ones will be assigned to each selected thing.
Thing Edit form: you can now double-click on thing type to apply the changes and close the form.