diff --git a/radiant/ui/common/ImageFileSelector.cpp b/radiant/ui/common/ImageFileSelector.cpp
index 6e728ea8ae..3580eb549a 100644
--- a/radiant/ui/common/ImageFileSelector.cpp
+++ b/radiant/ui/common/ImageFileSelector.cpp
@@ -10,8 +10,10 @@ namespace
     const char* const WINDOW_TITLE = N_("Select Image File");
 }
 
-ImageFileSelector::ImageFileSelector(wxWindow* parent) :
-    DialogBase(_(WINDOW_TITLE), parent)
+ImageFileSelector::ImageFileSelector(wxWindow* parent, wxTextCtrl* targetControl) :
+    DialogBase(_(WINDOW_TITLE), parent),
+    _okButton(nullptr),
+    _targetControl(targetControl)
 {
     SetSizer(new wxBoxSizer(wxVERTICAL));
 
@@ -22,9 +24,14 @@ ImageFileSelector::ImageFileSelector(wxWindow* parent) :
 
     _treeView->AddSearchColumn(_columns.iconAndName);
     _treeView->SetExpandTopLevelItemsAfterPopulation(true);
+    _treeView->Bind(wxEVT_DATAVIEW_SELECTION_CHANGED, &ImageFileSelector::onTreeSelectionChanged, this);
+
+    auto dialogButtons = CreateStdDialogButtonSizer(wxOK | wxCANCEL);
+    _okButton = dialogButtons->GetAffirmativeButton();
+    _okButton->Disable();
 
     GetSizer()->Add(_treeView, 1, wxALL|wxEXPAND, 12);
-    GetSizer()->Add(CreateStdDialogButtonSizer(wxOK | wxCANCEL), 0, wxALIGN_RIGHT | wxBOTTOM | wxRIGHT, 12);
+    GetSizer()->Add(dialogButtons, 0, wxALIGN_RIGHT | wxBOTTOM | wxRIGHT, 12);
 
     FitToScreen(0.5f, 0.7f);
 }
@@ -33,7 +40,50 @@ int ImageFileSelector::ShowModal()
 {
     _treeView->Populate(std::make_shared<ImageFilePopulator>(_columns));
 
-    return DialogBase::ShowModal();
+    _previousValue = _targetControl->GetValue().ToStdString();
+
+    auto result = DialogBase::ShowModal();
+
+    if (result != wxID_OK)
+    {
+        // Restore the previous value on cancel
+        _targetControl->SetValue(_previousValue);
+    }
+
+    return result;
+}
+
+std::string ImageFileSelector::GetSelection()
+{
+    auto item = _treeView->GetSelection();
+    if (!item.IsOk()) return std::string();
+
+    wxutil::TreeModel::Row row(item, *_treeView->GetModel());
+
+    if (row[_columns.isFolder].getBool()) return std::string();
+
+    return row[_columns.fullName];
+}
+
+void ImageFileSelector::onTreeSelectionChanged(wxDataViewEvent& ev)
+{
+    auto item = _treeView->GetSelection();
+    
+    if (!item.IsOk())
+    {
+        _okButton->Disable();
+        return;
+    }
+
+    wxutil::TreeModel::Row row(item, *_treeView->GetModel());
+
+    bool isFolder = row[_columns.isFolder].getBool();
+    _okButton->Enable(!isFolder);
+
+    if (!isFolder)
+    {
+        _targetControl->SetValue(row[_columns.fullName].getString());
+    }
 }
 
 }
diff --git a/radiant/ui/common/ImageFileSelector.h b/radiant/ui/common/ImageFileSelector.h
index a7802dcaa3..44521ecb0f 100644
--- a/radiant/ui/common/ImageFileSelector.h
+++ b/radiant/ui/common/ImageFileSelector.h
@@ -2,6 +2,8 @@
 
 #include "wxutil/dialog/DialogBase.h"
 #include "wxutil/dataview/ResourceTreeView.h"
+#include <wx/button.h>
+#include <wx/textctrl.h>
 
 namespace ui
 {
@@ -16,10 +18,19 @@ class ImageFileSelector :
     wxutil::ResourceTreeView::Columns _columns;
     wxutil::ResourceTreeView* _treeView;
 
+    wxButton* _okButton;
+    wxTextCtrl* _targetControl;
+    std::string _previousValue;
+
 public:
-    ImageFileSelector(wxWindow* parent);
+    ImageFileSelector(wxWindow* parent, wxTextCtrl* targetControl);
 
     int ShowModal() override;
+
+    std::string GetSelection();
+
+private:
+    void onTreeSelectionChanged(wxDataViewEvent& ev);
 };
 
 }
diff --git a/radiant/ui/materials/MapExpressionEntry.h b/radiant/ui/materials/MapExpressionEntry.h
index db0212430e..0b88bd9286 100644
--- a/radiant/ui/materials/MapExpressionEntry.h
+++ b/radiant/ui/materials/MapExpressionEntry.h
@@ -46,12 +46,9 @@ class MapExpressionEntry :
 private:
     void onBrowseButtonClick(wxCommandEvent& ev)
     {
-        auto selector = new ImageFileSelector(this);
-
-        if (selector->ShowModal() == wxID_OK)
-        {
-            // TODO: assign expression
-        }
+        auto selector = new ImageFileSelector(this, _textEntry);
+        selector->ShowModal();
+        selector->Destroy();
     }
 };